Neurotrophins in clinical diagnostics: pathophysiology and laboratory investigation

The Influence of Neurotrophins on the Brain-Lung Axis: Conception, Pregnancy, and Neonatal Period

Neurotrophins (NTs) are four small proteins produced by both neuronal and non-neuronal cells; they include nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4). NTs can exert their action through both genomic and non-genomic mechanisms by interacting with specific receptors. Initial studies on NTs have identified them only as functional molecules of the nervous system. However, recent research have shown that some tissues and organs (such as the lungs, skin, and skeletal and smooth muscle) as well as some structural cells can secrete and respond to NTs. In addition, NTs perform several roles in normal and pathological conditions at different anatomical sites, in both fetal and postnatal life. During pregnancy, NTs are produced by the mother, placenta, and fetus. They play a pivotal role in the pre-implantation process and in placental and embryonic development; they are also involved in the development of the brain and respiratory system. In the postnatal period, it appears that NTs are associated with some diseases, such as sudden infant death syndrome (SIDS), asthma, congenital central hypoventilation syndrome (CCHS), and bronchopulmonary dysplasia (BPD).

The early life growth of head circumference, weight, and height in infants with autism spectrum disorders: a systematic review

BACKGROUNDS

The Autism spectrum disorder (ASD) prevalence has increased significantly over the past two decades. This review summarizes the current knowledge of the association between the early life growth of head circumference (HC), weight, and height with ASD in infants.

METHODS

PubMed, Scopus, Science Direct, and Google Scholar databases were searched up to November 2021 using relevant keywords. All original articles are written in English evaluating the early life growth of HC, weight, and height in infants with ASD were eligible for the present review.

RESULTS

Totally, 23 articles involving 4959 infants were included in this review. Of 13 studies that evaluated HC of infants at birth, 10 studies (83.33%) showed that the HC at the birth of autistic children was similar to that of the average found in the control group. Among 21 studies that evaluated the HC and weight status in infants, 19 studies (90.47%) showed that autistic children had larger HC and weight than the control group or abnormal acceleration of head growth during infancy. Height growth of infants was investigated in 13 studies, of which 10 cases (76.92%) reported that infants with ASD were significantly longer than control groups. Most of he included studies had a good quality.

CONCLUSIONS

The findings suggest that in infants with ASD, without the contribution of birth growth factors and sex of the child, the growth of HC, weight, and height probably was faster than in infants with normal development, in early life. Therefore, these measurements might be useful as initial predictive biomarkers for the risk of developing ASD.

Brain-derived neurotrophic factor: focus on the pathogenesis of multiple myeloma and the development of treatment-induced peripheral neuropathy

For many years, intensive research has been carried out on the in-depth understanding of the pathogenesis of multiple myeloma (MM). Nevertheless, the multifactorial nature of the disease, the development of drug resistance, and the side effects of therapy, make it difficult to effectively treat patients. One of the many factors involved in the pathogenesis of MM is brain-derived neurotrophic factor (BDNF). This factor is widely described as a neuroregenerative and neuroprotective agent, but it also regulates non-neuronal cell functions, such as proliferation, apoptosis, and viability. Therefore, BDNF appears to be a good therapeutic target in MM. On the other hand, its decreased concentration during treatment closely correlates with the development of peripheral neuropathy (PN). BDNF dualism requires a detailed understanding of its action on individual molecular mechanisms. Perhaps the optimization of the BDNF level will contribute to the improvement of MM treatment and the reduction of chemotherapy side effects.

Early nutritional intake influences the serum levels of nerve growth factor (NGF) and brain-derived neurotrophic factor in preterm newborns

Introduction

Parenteral nutrition (PN) may have detrimental effects on neurodevelopment in preterm newborns. Moreover, enteral nutrition (EN) seems to be protective. To understand the mechanisms of how neurological development can be influenced by the route of administration of nutritional intake, we investigated the relationship between the serum levels of the nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) and nutritional intake received in early life by preterm newborns.

Materials and methods

Specimens of blood were obtained at 28 days of life (DOL) for NGF/BDNF determination in neonates <32 weeks of gestation and/or with birth weight <1,500 g, consecutively observed in the neonatal intensive care unit. We analyzed the relation between amino acid content and energy intake and NGF/BDNF measurements at 28 DOL. PN protein intake was referred to as the total amounts of amino acid intake received daily.

Results

We enrolled 20 newborns (gestational age 30.45 ± 1.76 weeks, birth weight 1,340 ± 352.63 g). Serum NGF value at 28 DOL was positively correlated with enteral protein and energy intake (r = 0.767; r = 0.746, p < 0.001), whereas, negatively correlated with parenteral amino acid and energy intake (r = −0.652, p < 0.001; r = −0.466, p < 0.05). Similar significant correlations were described between BDNF level at 28 DOL and enteral energy intake (r = 0.493, p < 0.05). Multivariate regression analysis showed that NGF level at 28 DOL depends on enteral protein and energy intake administrated in the 1st week of life.

Conclusion

Neurotrophin values varied according to the route of nutrition administration in preterm newborns. NGF/BDNF serum levels are influenced positively and negatively by EN and PN, respectively.

Stratification of rheumatoid arthritis cohort using Ayurveda based deep phenotyping approach identifies novel genes in a GWAS

Background and aim

Genome wide association studies have scaled up both in terms of sample size and range of complex disorders investigated, but these have explained relatively little phenotypic variance. Of the several reasons, phenotypic heterogeneity seems to be a likely contributor for missing out genetic associations of large effects. Ayurveda, the traditional Indian system of medicine is one such tool which adopts a holistic deep phenotyping approach and classifies individuals based on their body constitution/prakriti. We hypothesized that Ayurveda based phenotypic stratification of healthy and diseased individuals will allow us to achieve much desired homogeneous cohorts which would facilitate detection of genetic association of large effects. In this proof of concept study, we performed a genome wide association testing of clinically diagnosed rheumatoid arthritis patients and healthy controls, who were re-phenotyped into Vata, Pitta and Kapha predominant prakriti sub-groups.

Experimental procedure

Genotypes of rheumatoid arthritis cases (Vata = 49; Pitta = 117; Kapha = 78) and controls (Vata = 33; Pitta = 175; Kapha = 85) were retrieved from the total genotype data, used in a recent genome-wide association study performed in our laboratory. A total of 528461 SNPs were included after quality control. Prakriti-wise genome-wide association analysis was employed.

Results and conclusion

This study identified (i) prakriti-specific novel disease risk genes of high effect sizes; (ii) putative candidates of novel therapeutic potential; and (iii) a good correlation between genetic findings and clinical knowledge in Ayurveda. Adopting Ayurveda based deep phenotyping may facilitate explaining hitherto undiscovered heritability in complex traits and may propel much needed progress in personalized medicine.

Transcriptional Activity of Neurotrophins Genes and Their Receptors in the Peripheral Blood in Patients with Thyroid Diseases in Bukovinian Population of Ukraine

Objective. Thyroid hormone has an especially strong impact on central nervous system development, and thyroid hormone deficiency has been shown to result in severe mental retardation. It is crucial to identify compensatory mechanisms that can be involved in improving cognitive function and the quality of life of patients with hypothyroidism. Methods: We used the pathway-specific PCR array (Neurotrophins and Receptors RT2 Profiler PCR Array, QIAGEN, Germany) to identify and validate neurotrophins genes and their receptor expression in patients with thyroid pathology and control group. Results: The analysis of gene expression of neurotrophins and their receptors showed that CRHBP, FRS2, FRS3, GFRA1, GFRA2, GMFB, NGF, NRG2, NRG4, NTF4, TRO, and VGF significantly decreased their expression in Group 3, which includes the patients with postoperative hypothyroidism. The patients with primary hypothyroidism stemming from AIT had significantly reduced expression of CRHBP, GFRA1, GFRA2, GMFB, NGF, PTGER2, and VGF, while the expression of NRG4 and TRO increased. In Group 3, which includes the patients with AIT and elevated serum anti-Tg and anti-TPO autoantibodies, the mRNA levels of GFRA2, NGF, NRG2, NTF4, NGF, PTGER were reduced, and the expression of CRHBP, FRS2, FRS3 GFRA1, GMFB, NRG4, TRO, and VGF significantly increased. Conclusion: These results indicate significant variability in the transcriptional activity of the genes of encoding neurotrophins and their receptors in the peripheral blood in people with thyroid diseases.

Neurotrophic Factor Levels in Preterm Infants: A Systematic Review and Meta-Analysis

Objectives: Through a systematic review and meta-analysis of the literature we aimed to compare the levels of BDNF, NGF, NT-3, NT-4, and GDNF between human term and preterm infants, and investigate factors implicated in the variability of effect size estimates. Methods: The analysis was performed in three online databases, MEDLINE Complete, PsycINFO, and CINAHL. A random effects model was used to calculate the standardized mean difference (SMD) of neurotrophic factor levels in preterm infants vs. term within a 95% confidence interval (CI). To explore sources of heterogeneity meta-regression models were implemented. Results: Sixteen studies were included in this meta-analysis. A combined sample of 1,379 preterm and 1,286 term newborns were evaluated. We identified significant lower BDNF (SMD = -0.32; 95% CI: -0.59, -0.06; p = 0.014) and NT-3 (SMD = -0.31; 95% CI: -0.52, -0.09; p = 0.004) levels in preterm compared to term infants. No significant difference was observed in NGF and NT-4 levels between groups. Given that only two effect sizes were generated for GDNF levels, no meta-analytical model was performed. Meta-regression models revealed sample type (placental tissue, cerebrospinal fluid, peripheral blood, and umbilical cord blood) as a significant moderator of heterogeneity for BDNF meta-analysis. No significant associations were found for gestational week, birth weight, and clinical comorbidity of newborns with effect sizes. Conclusions: Our findings indicated that lower BDNF and NT-3 levels may be associated with preterm birth. Future studies with larger samples sizes should investigate neurodevelopmental manifestations resulting from neurotrophic factor dysregulation among preterm infants.

Neurotrophin Regulation and Signaling in Airway Smooth Muscle

Structural and functional aspects of bronchial airways are key throughout life and play critical roles in diseases such as asthma. Asthma involves functional changes such as airway irritability and hyperreactivity, as well as structural changes such as enhanced cellular proliferation of airway smooth muscle (ASM), epithelium, and fibroblasts, and altered extracellular matrix (ECM) and fibrosis, all modulated by factors such as inflammation. There is now increasing recognition that disease maintenance following initial triggers involves a prominent role for resident nonimmune airway cells that secrete growth factors with pleiotropic autocrine and paracrine effects. The family of neurotrophins may be particularly relevant in this regard. Long recognized in the nervous system, classical neurotrophins such as brain-derived neurotrophic factor (BDNF) and nonclassical ligands such as glial-derived neurotrophic factor (GDNF) are now known to be expressed and functional in non-neuronal systems including lung. However, the sources, targets, regulation, and downstream effects are still under investigation. In this chapter, we discuss current state of knowledge and future directions regarding BDNF and GDNF in airway physiology and on pathophysiological contributions in asthma.

Effects of long-term administration of Multi-Strain Probiotic on circulating levels of BDNF, NGF, IL-6 and mental health in patients with multiple sclerosis: a randomized, double-blind, placebo-controlled trial

Background: Mental disorders is one of the main causes of disability and lower life expectancy among patients with Multiple Sclerosis (MS). The present trial aimed to examine the efficacy of multi-strain probiotic supplementation on circulating levels of BDNF, NGF, IL-6 and mental health in patients with MS.Methods: This trial was conducted among 70 patients with MS that referred to the MS Association. Patients were randomized into intervention and control groups to receive 2 multi-strain probiotic capsules or placebo, daily for six months. Serum BDNF, NGF and IL-6 was measured by ELISA kits. Mental health parameters were assessed by valid questionnaires in the baseline and end of the study.Results: Of the 70 patients enrolled in this study, 65 subjects were included in the final analysis. From baseline to 6 months, probiotic supplementation resulted in a significant increase in BDNF and a significant reduction in the IL-6 levels (P < 0.001). Our findings revealed that probiotic supplementation compared to placebo caused a significant improvement in the general health questionnaire-28 (GHQ-28) (-5.31 ± 4.62 vs. -1.81 ± 4.23; P = 0.002), Beck Depression Inventory-II (BDI-II) (-4.81 ± 0.79 vs. -1.90 ± 0.96; P = 0.001), Fatigue Severity Scale (FSS) (-3.81 ± 6.56 vs. 0.24 ± 5.44; P = 0.007) and Pain Rating Index (PRI) (-3.15 ± 4.51 vs. -0.09 ± 3.67; P = 0.004). However, we not found any significant difference between the two groups in other factors (P > 0.05).Conclusion: Overall, six months of probiotic supplementation resulted in greater improvement in mental health parameters.

Early changes of serum BDNF and SSRI response in adolescents with major depressive disorder

BACKGROUND

Recent evidence suggests that brain-derived neurotrophic factor (BDNF) levels and their early changes may predict antidepressant response in adults with major depressive disorder (MDD). However, in adolescents, BDNF levels in depression and their changes during antidepressant treatment are relatively unknown. We aimed to investigate whether pre-treatment BDNF levels and their early changes predict antidepressant response in depressed adolescents.

METHODS

The study included 83 MDD adolescents and 52 healthy controls aged 12 to 17 years. All depressed adolescents were treated with escitalopram in an 8 week, open-label trial. Depression severity and serum BDNF level at baseline, and weeks 2 and 8 were measured with the Children's Depression Rating Scale-Revised (CDRS-R) and ELISA, respectively.

RESULTS

Responders showed a significant decrease in BDNF levels at week 2 but non-responders and healthy controls had no changes in BDNF levels at week 2. The early decrease (baseline - week 2) of BDNF levels predicted SSRI response with moderate sensitivity and specificity. Logistic regression analysis revealed that early BDNF decrease predicted SSRI response at week 8 after controlling for other demographic and clinical variables.

LIMITATIONS

The follow-up duration of the study was limited in 8 weeks. It remains possible that serum BDNF levels would have changed with longer treatment.

CONCLUSIONS

This is the first longitudinal study to investigate the effect of antidepressants on BDNF levels in adolescents with MDD. Our findings suggest that a decrease of serum BDNF levels in early phase of SSRI treatment may be associated later SSRI response in adolescents with MDD.

Neurotrophin-3 acts on the endothelial-mesenchymal transition of heterotopic ossification in rats

Despite the fact that extensive studies have focused on heterotopic ossification (HO), its molecular mechanism remains unclear. The endothelial-mesenchymal transition (EndMT), which may be partially modulated by neuroendocrine cytokines is thought to play a major role in HO. Neurotrophin-3 (NT-3), which has neuroendocrine characteristics is believed to promote skeletal remodeling. Herein, we suggest that that NT-3 may promote HO formation through regulation of EndMT. Here, we used an in vivo model of HO and an in vitro model of EndMT induction to elucidate the effect and underlying mechanism of NT-3 on EndMT in HO. Our results showed that heterotopic bone and cartilage arose from EndMT and NT-3 promoted HO formation in vivo. Our in vitro results showed that NT-3 up-regulated mesenchymal markers (FSP-1, α-SMA and N-cadherin) and mesenchymal stem cell (MSC) markers (STRO-1, CD44 and CD90) and down-regulated endothelial markers (Tie-1, VE-cadherin and CD31). Moreover, NT-3 enhanced a chondrogenesis marker (Sox9) and osteogenesis markers (OCN and Runx2) via activation of EndMT. However, both EndMT specific inhibitor and tropomyosin-related kinase C (TrkC) specific inhibitor rescued NT-3-induced HO formation and EndMT induction in vivo and in vitro. In conclusion, our findings demonstrate that NT-3 promotes HO formation via modulation of EndMT both in vivo and in vitro, which offers a new potential target for the prevention and therapy of HO.

Direct and indirect evidences of BDNF and NGF as key modulators in depression: role of antidepressants treatment

PURPOSE

Depression is one of the most prevalent, recurrent and life-threatening mental illnesses. However, the precise mechanism underlying the disorder is not yet clearly understood. It is therefore, essential to identify the novel biomarkers which may help in the development of effective treatment.

METHODS

In this milieu, the profile of the brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) were considered as biomarkers in the light of pathophysiology of depression and its treatment.

RESULTS

Previously, we have reported that BDNF level in the postmortem brain of suicide victims was significantly lower than those of normal controls. We also found decreased BDNF levels in the specific brain regions of the learned helplessness model of depression in rat, and was found to increase normal level following chronic fluoxetine hydrochloride treatment. NGF is another important member of neurotrophin, which is dysregulated in the pathophysiology of depression in some models of peripheral nerve damage and stress. The results shown evidences of the effect of antidepressants on modulating depression via the NGF in preclinical and clinical models of depression, but conflicted, therefore make it currently difficult to affirm the therapeutic role of antidepressants.

CONCLUSIONS

Here, we review some of the preclinical and clinical studies aimed at disclosing the role of BDNF and NGF mediated pathophysiological mechanisms of depression and the new therapeutic approaches targeting those key molecules. In addition, an important link between BDNF, NGF and depression has been discussed in the light of current existing knowledge.

Brain-derived neurotrophic factor, a new soluble biomarker for malignant pleural mesothelioma involved in angiogenesis

Malignant pleural mesothelioma (MPM) is a rare and aggressive cancer related to asbestos exposure. The discovery of soluble biomarkers with diagnostic/prognostic and/or therapeutic properties would improve therapeutic care of MPM patients. Currently, soluble biomarkers described present weaknesses preventing their use in clinic. This study aimed at evaluating brain-derived neurotrophic factor (BDNF), we previously identified using transcriptomic approach, in MPM. We observed that high BDNF expression, at the mRNA level in tumors or at the protein level in pleural effusions (PE), was a specific hallmark of MPM samples. This protein presented significant but limited diagnostic properties (area under the curve (AUC) = 0.6972, p < 0.0001). Interestingly, high BDNF gene expression and PE concentration were predictive of shorter MPM patient survival (13.0 vs 8.3 months, p < 0.0001, in PE). Finally, BDNF did not affect MPM cell oncogenic properties but was implicated in PE-induced angiogenesis. In conclusion, BDNF appears to be a new interesting biomarker for MPM and could also be a new therapeutic target regarding its implication in angiogenesis.

Association of Brain-Derived Neurotrophic Factor and Vitamin D with Depression and Obesity: A Population-Based Study

BACKGROUND

Depression and obesity are widespread and closely linked. Brain-derived neurotrophic factor (BDNF) and vitamin D are both assumed to be associated with depression and obesity. Little is known about the interplay between vitamin D and BDNF. We explored the putative associations and interactions between serum BDNF and vitamin D levels with depressive symptoms and abdominal obesity in a large population-based cohort.

METHODS

Data were obtained from the population-based Study of Health in Pomerania (SHIP)-Trend (n = 3,926). The associations of serum BDNF and vitamin D levels with depressive symptoms (measured using the Patient Health Questionnaire) were assessed with binary and multinomial logistic regression models. The associations of serum BDNF and vitamin D levels with obesity (measured by the waist-to-hip ratio [WHR]) were assessed with binary logistic and linear regression models with restricted cubic splines.

RESULTS

Logistic regression models revealed inverse associations of vitamin D with depression (OR = 0.966; 95% CI 0.951-0.981) and obesity (OR = 0.976; 95% CI 0.967-0.985). No linear association of serum BDNF with depression or obesity was found. However, linear regression models revealed a U-shaped association of BDNF with WHR (p < 0.001).

CONCLUSION

Vitamin D was inversely associated with depression and obesity. BDNF was associated with abdominal obesity, but not with depression. At the population level, our results support the relevant roles of vitamin D and BDNF in mental and physical health-related outcomes.

Seasonality and BDNF polymorphism influences depression outcome in patients with atopic dermatitis and psoriasis

OBJECTIVES

To examine the effect of seasonality and rs6265 genotype on depression outcome and brain-derived neurotrophic factor (BDNF) level with dermatitis patients from onset through remission.

METHODS

Atopic dermatitis (AD, 56) and psoriasis (PS, 33) patients and healthy controls (HC, 49) were recruited over the 2014 calendar year. Patients were subdivided by immunoglobulin E (IgE) sensitivity (AD only), season and rs6265 genotype. Assessments were performed at onset and week 10 (Hamilton Depression Rating Scale [HAM-D], SCORAD/PASI, IgE, BDNF). Patients received standard corticosteroid and antihistamine interventions.

RESULTS

All patients responded to corticosteroid treatment. Seasonally differential outcomes were observed in all groups. HAM-D was elevated at onset and improved over 10 weeks: AD cohort 1 (autumn/winter, AD-1) patients improved and AD cohort 2 (spring/summer, AD-2) patients remained elevated. BDNF levels were elevated in AD and seasonal differential: AD-2 declined at 10 weeks, whereas AD-1 remained high (intrinsic AD) or elevated further (extrinsic AD). PS cohort 2 declined to below control at 10 weeks. AD Val/Val had persistently elevated HAM-D and AD Val/Met were either normal (AD-1) or persistently elevated (AD-2).

CONCLUSIONS

Findings presented here suggest a strong influence of seasonality on depression outcome and BDNF expression in AD and PS and likely reflect separate patient populations which differentially respond to environment-based stressors.

Decoding the Regulatory Landscape of Ageing in Musculoskeletal Engineered Tissues Using Genome-Wide DNA Methylation and RNASeq

Mesenchymal stem cells (MSC) are capable of multipotent differentiation into connective tissues and as such are an attractive source for autologous cell-based regenerative medicine and tissue engineering. Epigenetic mechanisms, like DNA methylation, contribute to the changes in gene expression in ageing. However there was a lack of sufficient knowledge of the role that differential methylation plays during chondrogenic, osteogenic and tenogenic differentiation from ageing MSCs. This study undertook genome level determination of the effects of DNA methylation on expression in engineered tissues from chronologically aged MSCs. We compiled unique DNA methylation signatures from chondrogenic, osteogenic, and tenogenic engineered tissues derived from young; n = 4 (21.8 years ± 2.4 SD) and old; n = 4 (65.5 years±8.3SD) human MSCs donors using the Illumina HumanMethylation 450 Beadchip arrays and compared these to gene expression by RNA sequencing. Unique and common signatures of global DNA methylation were identified. There were 201, 67 and 32 chondrogenic, osteogenic and tenogenic age-related DE protein-coding genes respectively. Findings inferred the nature of the transcript networks was predominantly for 'cell death and survival', 'cell morphology', and 'cell growth and proliferation'. Further studies are required to validate if this gene expression effect translates to cell events. Alternative splicing (AS) was dysregulated in ageing with 119, 21 and 9 differential splicing events identified in chondrogenic, osteogenic and tenogenic respectively, and enrichment in genes associated principally with metabolic processes. Gene ontology analysis of differentially methylated loci indicated age-related enrichment for all engineered tissue types in 'skeletal system morphogenesis', 'regulation of cell proliferation' and 'regulation of transcription' suggesting that dynamic epigenetic modifications may occur in genes associated with shared and distinct pathways dependent upon engineered tissue type. An altered phenotype in engineered tissues was observed with ageing at numerous levels. These changes represent novel insights into the ageing process, with implications for stem cell therapies in older patients. In addition we have identified a number of tissue-dependant pathways, which warrant further studies.

Are the changes in the peripheral brain-derived neurotrophic factor levels due to platelet activation?

Brain-derived neurotrophic factor (BDNF) plays an important role in central nervous system development, neurogenesis and neuronal plasticity. BDNF is also expressed in several non-neuronal tissues, and it could play an important role in other processes, such as cancer, angiogenesis, etc. Platelets are the major source of peripheral BDNF. However, platelets also contain high amounts of serotonin; they express specific surface receptors during activation, and a multitude of pro-inflammatory and immunomodulatory bioactive compounds are secreted from the granules. Until recently, there was insufficient knowledge regarding the relationship between BDNF and platelets. Recent studies showed that BDNF is present in two distinct pools in platelets, in α-granules and in the cytoplasm, and only the BDNF in the granules is secreted following stimulation, representing 30% of the total BDNF in platelets. BDNF has an important role in the pathophysiology of depression. Low levels of serum BDNF have been described in patients with major depressive disorder, and BDNF levels increased with chronic antidepressant treatment. Interestingly, there is an association between depression and platelet function. This review analyzed studies that evaluated the relationship between BDNF and platelet activation and the effect of treatments on both parameters. Only a few studies consider this possible confounding factor, and it could be very important in diseases such as depression, which show changes in both parameters.

Serum BDNF as a peripheral biomarker of treatment-resistant depression and the rapid antidepressant response: A comparison of ketamine and ECT

BACKGROUND

Ketamine is associated with rapid antidepressant efficacy but the biological mechanisms underpinning this effect are unclear. Serum brain-derived neurotrophic factor (sBDNF) is a potential circulating biomarker of treatment-resistant depression (TRD) and ketamine response but it is unclear if this is a common target of both ketamine and electroconvulsive therapy (ECT), the current gold standard for TRD. Moreover, the impact of multiple ketamine infusions on sBDNF has not yet been established.

METHODS

Thirty five TRD patients with a current DSM-IV diagnosis of recurrent depressive disorder received up to 12 ECT sessions (N=17) or up to three intravenous infusions of low-dose (0.5mg/kg) ketamine (N=18). Blood samples were taken over the course of the study for assessment of sBDNF. Symptom severity and response were monitored using the 17-item Hamilton Depression Rating Scale (HDRS). sBDNF was assessed in 20 healthy controls to allow comparison with TRD patients.

RESULTS

As expected, sBDNF was lower in TRD patients at baseline compared to healthy controls. Ketamine and ECT treatment were both associated with significant reductions in depressive symptoms. However, sBDNF was significantly elevated only at one week following the first ketamine infusion in those classified as responders one week later. sBDNF was not elevated following subsequent infusions. ECT reduced depressive symptoms, as expected, but was not associated with an enhancement in BDNF.

LIMITATIONS

Patients continued with their psychotropic medications throughout this trial.

CONCLUSIONS

SBDNF normalisation does not appear to be a prerequisite for symptomatic improvement in TRD following ketamine or ECT treatment.

Autism with intellectual disability related to dynamics of head circumference growth during early infancy

BACKGROUND

It is not yet definitively known whether dynamic features of head circumference growth are associated with autism. To address this issue, we carried out a nested matched case-control study using data from national well baby clinics in Finland; autism cases were identified from the Finnish Hospital and Outpatient Discharge Registry.

METHODS

A nonparametric Bayesian method was used to construct growth velocity trajectories between birth and 2 years of age in autism cases and matched control subjects (n = 468 in main analyses, 1:1 matched control subjects). Estimates of odds ratios for autism risk in relation to the growth velocities were obtained using conditional logistic regression.

RESULTS

Growth velocity of head circumference at 3 months of age, adjusting for gestational age at birth and maternal age, is significantly associated with autism (p = .014); the finding was observed in subjects with comorbid intellectual disability (ID) (p = .025) but not in those without ID (p = .15). Height growth velocity among subjects with autism and without ID is significantly associated with autism at 6 months (p = .007), and weight growth velocity at 18 months without ID (p = .02) and 24 months without ID (p = .042) and with ID (p = .037).

CONCLUSIONS

Acceleration in head circumference growth is associated with autism with comorbid ID at 3 months but not subsequently. This association is unrelated to acceleration in height and weight, which are not strongly associated with autism until after 6 months.

Focus on ECT seizure quality: serum BDNF as a peripheral biomarker in depressed patients

Electroconvulsive therapy (ECT) is a well-established, safe and effective treatment in severest or drug-resistant affective disorders. The potential relation between any peripheral biological marker and the seizure quality as a surrogate for treatment efficacy has not been investigated so far. We prospectively examined serum brain-derived neurotrophic factor (BDNF) levels in 20 patients with major depression before and after electroconvulsive therapy. A seizure quality sum score for every ECT session was build up on the basis of the seizure duration, seizure amplitude, central inhibition, interhemispheric coherence and sympathetic activation. Serum BDNF levels were significantly higher after ECT (P = 0.036). In the linear regression analysis, a significant correlation of the serum BDNF levels and the time between the last ECT and the blood withdrawal (P = 0.01) was observed. The ANOVA revealed a significant influence of the interval between the last ECT and the blood withdrawal (P = 0.0017) as well as the seizure quality (P = 0.038) on the variance of BDNF serum levels. Our data corroborate the neurotrophin hypothesis suggesting an ECT-induced central BDNF rise leading to a delayed (>6 days) and increased equilibrium of the peripheral BDNF. The association of seizure adequacy with a BDNF rise might underline the importance of monitoring seizure quality markers in daily practice.

Neurotrophic factors in women with crack cocaine dependence during early abstinence: the role of early life stress

BACKGROUND

Neurotrophic factors have been investigated in the pathophysiology of alcohol and drug dependence and have been related to early life stress driving developmental programming of neuroendocrine systems.

METHODS

We conducted a follow-up study that aimed to assess the plasma levels of glial cell line-derived neurotrophic factor (GDNF), brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), neurotrophin-3 (NT3) and neurotrophin-4/5 (NT4/5) in crack users during 3 weeks of early abstinence in comparison with healthy controls. We performed a comprehensive clinical assessment in female inpatients with crack cocaine dependence (separated into 2 groups: participants with (CSA+) and without (CSA-) a history of childhood sexual abuse) and a group of nonuser control participants.

RESULTS

Our sample included 104 women with crack cocaine dependence and 22 controls; of the women who used crack cocaine, 22 had a history of childhood sexual abuse and 82 did not. The GDNF plasma levels in the CSA+ group increased dramatically during 3 weeks of detoxification. In contrast, those in the CSA- group showed lower and stable levels of GDNF under the same conditions. Compared with the control group, BDNF plasma levels remained elevated and NGF levels were reduced during early abstinence. We found no differences in NT3 and NT4/5 between the patients and controls. However, within-group analyses showed that the CSA+ group exhibited higher levels of NT4/5 than the CSA- group at the end of detoxification.

LIMITATIONS

Some of the participants were using neuroleptics, mood stabilizers or antidepressants; our sample included only women; memory bias could not be controlled; and we did not investigate the possible confounding effects of other forms of stress during childhood.

CONCLUSION

This study supports the association between early life stress and peripheral neurotrophic factor levels in crack cocaine users. During early abstinence, plasmastic GDNF and NT4/5 were the only factors to show changes associated with a history of childhood sexual abuse.

Brain-derived neurotrophic factor in the airways

In addition to their well-known roles in the nervous system, there is increasing recognition that neurotrophins such as brain derived neurotrophic factor (BDNF) as well as their receptors are expressed in peripheral tissues including the lung, and can thus potentially contribute to both normal physiology and pathophysiology of several diseases. The relevance of this family of growth factors lies in emerging clinical data indicating altered neurotrophin levels and function in a range of diseases including neonatal and adult asthma, sinusitis, influenza, and lung cancer. The current review focuses on 1) the importance of BDNF expression and signaling mechanisms in early airway and lung development, critical to both normal neonatal lung function and also its disruption in prematurity and insults such as inflammation and infection; 2) how BDNF, potentially derived from airway nerves modulate neurogenic control of airway tone, a key aspect of airway reflexes as well as dysfunctional responses to allergic inflammation; 3) the emerging idea that local BDNF production by resident airway cells such as epithelium and airway smooth muscle can contribute to normal airway structure and function, and to airway hyperreactivity and remodeling in diseases such as asthma. Furthermore, given its pleiotropic effects in the airway, BDNF may be a novel and appealing therapeutic target.

Plasma brain-derived neurotrophic factor and prefrontal white matter integrity in late-onset depression and normal aging

OBJECTIVE

To explore the relationship between brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF), cerebral deep white matter lesions (DWMLs), and measures of white matter integrity in patients with late-onset depression, with respect to vascular risk factors.

METHOD

We examined 22 patients with late-onset depression and 22 matched controls. Quantification of plasma BDNF and VEGF levels were performed with enzyme-linked immunosorbent assay (ELISA) kits. Measures of white matter integrity comprised apparent diffusion coefficient (ADC) and fractional anisotropy (FA), obtained by diffusion tensor imaging (DTI). Effects of DWMLs, FA, ADC, and vascular risk factors on BDNF and VEGF were assessed using multiple linear regression.

RESULTS

The BDNF and VEGF levels did not differ significantly between groups. With pooled data for patients and controls, the BDNF level was positively associated with both number (t = 2.14, P = 0.039) and volume (t = 2.04, P = 0.048) of prefrontal DWMLs and negatively associated with FA in prefrontal normal-appearing white matter (t = -2.40, P = 0.02), adjusted for age and gender. Smoking and hypercholesterolemia was positively associated with the BDNF (t = 2.36, P = 0.023) and VEGF levels (t = 2.28, P = 0.028), respectively.

CONCLUSION

Our results suggest a role for BDNF in the complex pathophysiologic mechanisms underlying DWMLs in both normal aging and late-onset depression.

Quality and timing of stressors differentially impact on brain plasticity and neuroendocrine-immune function in mice

A growing body of evidence suggests that psychological stress is a major risk factor for psychiatric disorders. The basic mechanisms are still under investigation but involve changes in neuroendocrine-immune interactions, ultimately affecting brain plasticity. In this study we characterized central and peripheral effects of different stressors, applied for different time lengths, in adult male C57BL/6J mice. We compared the effects of repeated (7 versus 21 days) restraint stress (RS) and chronic disruption of social hierarchy (SS) on neuroendocrine (corticosterone) and immune function (cytokines and splenic apoptosis) and on a marker of brain plasticity (brain-derived neurotrophic factor, BDNF ). Neuroendocrine activation did not differ between SS and control subjects; by contrast, the RS group showed a strong neuroendocrine response characterized by a specific time-dependent profile. Immune function and hippocampal BDNF levels were inversely related to hypothalamic-pituitary-adrenal axis activation. These data show a fine modulation of the crosstalk between central and peripheral pathways of adaptation and plasticity and suggest that the length of stress exposure is crucial to determine its final outcome on health or disease.

Release reaction of brain-derived neurotrophic factor (BDNF) through PAR1 activation and its two distinct pools in human platelets

Brain-derived neurotrophic factor (BDNF) is a cytokine that plays important roles in the survival, development, and plasticity of neurons. BDNF is also expressed in peripheral tissues and cells. In this article, we report the BDNF release reaction through thrombin stimulation and its localization in human platelets. Platelets from healthy volunteers were subjected to PAR1-AP or PAR4-AP stimulation. Release of BDNF was measured by ELISA. Localization of BDNF in resting and thrombin-activated platelets was examined by immunoelectron microscopy and sucrose gradient ultracentrifugation following western blotting. BDNF was released dose-dependently with PAR1-AP concentrations with drastic release at low PAR1-AP concentrations and gently release at high PAR1-AP concentrations. Maximum BDNF release was approximately 37% at 132 μM PAR1-AP. In contrast, 3.8% BDNF was released with 1.13 mM PAR4-AP stimulation. In immunoelectron microscopy and sucrose gradient ultracentrifugation analyses, BDNF was detected not only in α-granules but also cytoplasm in of the resting platelets, and it was distributed in the swollen open canalicular system fused to α-granules at 1 min and disappeared at 5 min after stimulation by thrombin. However, BDNF in cytoplasm remained throughout platelet activation. In conclusions, we demonstrate that BDNF is released from platelets through predominately PAR1 regulation. Furthermore, we identified two pools of BDNF in the α-granules and cytoplasm of human platelets, and only BDNF in α-granules is released through platelet activation.

Adipocytokines, gut hormones and growth factors in anorexia nervosa

Anorexia nervosa is a complex eating disorder of unknown etiology which affects adolescent girls and young women and leads to chronic malnutrition. Clinical manifestations of prolonged semistarvation include a variety of physical features and psychiatric disorders. The study of different biological factors involved in the pathophysiology of anorexia nervosa is an area of active interest. In this review we have described the role of adipocytokines, neurotrophins, peptides of the gastrointestinal system and growth factors in appetite regulation, energy balance and insulin sensitivity in anorexia nervosa patients.

Measurements in the Blood of BDNF for RA Patients and in Response to Anti-TNF Treatment Help Us to Clarify the Magnitude of Centrally Related Pain and to Explain the Relief of This Pain upon Treatment

Brain-derived neurotrophic factor (BDNF) is a neurotrophin with functions related to neuronal survival/proliferation processes and inflammation. BDNF is also an important central pain mediator. The levels of BDNF have been found to be high for RA patients with severe disease and to become lowered in response to anti-TNF treatment. New information says that the levels of BDNF in the blood parallel the BDNF concentrations in the brain and that BDNF can pass the blood-brain barrier. Furthermore, most of the circulating BDNF is produced in the brain. Habitual and regular exercise, in contrast to temporary exercise, does also lead to a lowering of BDNF blood levels. Both anti-TNF treatment and habitual and regular exercise do have pain-relieving effects. It might be that the pain-relieving effect of anti-TNF treatment is related to an affection of central neuronal regions, hereby influencing BDNF production. Measurements of BDNF in the blood help us to clarify the magnitude of centrally related pain for RA patients and help us to explain the relief of this pain in response to anti-TNF treatment.

Neurotrophins induce nitric oxide generation in human pulmonary artery endothelial cells

AIMS

Members of the growth factor family of neurotrophins [NTs; e.g. brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT3)] and their high-affinity receptors (tropomyosin-related kinase; Trk) and low-affinity receptors p75 neurotrophin receptor (p75NTR) have been localized to pulmonary artery (PA) in humans. However, their role is unclear. Based on previous findings of NTs and their receptors within the pulmonary endothelium, we tested the hypothesis that NTs induce nitric oxide (NO) production in pulmonary endothelial cells (ECs), thus contributing to vasodilation.

METHODS AND RESULTS

In human pulmonary artery ECs loaded with the NO-sensitive fluorescent dye diaminofluorescein-2, both BDNF and NT3 (100 pM, 1 nM, and 10 nM) acutely (<10 min) and substantially increased fluorescence levels in a concentration-dependent fashion (to levels comparable to that induced by 1 μM acetylcholine). NT-induced elevation of NO levels was blunted by the tyrosine kinase inhibitor K252a, the nitric oxide synthase (NOS) inhibitor N(G)-nitro-L-arginine methyl ester, the Ca(2+) chelator 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid, and the NO scavenger 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide. Suppression of TrkB or TrkC expression via siRNA as well as functional blockade of p75NTR prevented NT-induced NO elevation. Both BDNF and NT3 increased phosphorylation of Akt and endothelial NO synthase (eNOS). In endothelium-intact porcine PA rings, NTs increased cGMP and induced vasodilation in pre-contracted arteries.

CONCLUSION

These results indicate that NTs acutely modulate pulmonary endothelial NO production and contribute to relaxation of the pulmonary vasculature.

A novel BDNF polymorphism affects plasma protein levels in interaction with early adversity in rhesus macaques

Early stressful events can increase vulnerability for psychopathology, although knowledge on the effectors is still limited. In this report we describe the characterization of a single nucleotide polymorphism (SNP) in rhesus macaques, which results in a Val to Met transition in the pro-BDNF domain, similar to a well described variant in the human gene. Further, we tested the hypothesis that peripheral levels of BDNF, which is involved in the response to stress and in the pathophysiology of anxiety and depression, might be differentially affected in a non-human primate model of early adverse rearing in a genotype-dependent manner. Males and females rhesus macaques reared either with their mothers (MR), in peer-only groups (PR), or in a "surrogate/peer-reared" (SPR) condition with limited peer interactions, were used as experimental subjects. BDNF levels were determined at baseline on postnatal days (PND) 14, 30 and 60 by means of specific ELISA procedure. Data indicate that BDNF levels were increased as a result of peer-rearing and that this increase was moderated by the presence of the SNP. Overall these data indicate that a SNP, which results in a Val to Met transition in the pro-BDNF domain, is present in rhesus macaques and is able to affect BDNF peripheral levels, thus making this primate model a fundamental tool to study gene by environment interactions involving the BDNF gene.

Linkage and association study of neurotrophins and their receptors as novel susceptibility genes for childhood IgA nephropathy

Neurotrophins (NTs) and their receptors (NTRs) are known to be important for pathogenesis of various inflammatory diseases that occur in not only neuronal but also nonneuronal tissues, including kidney. Here, we investigated association between childhood IgA nephropathy (IgAN) and single nucleotide polymorphisms (SNPs) of genes encoding NTs [nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF)] and NTRs [nerve growth factor receptor (NGFR) and neurotrophic tyrosine kinase receptor 1-3 (NTRK1-3)]. The genotyping data of 197 patients and 289 control subjects revealed significant association between NGF SNP rs11102930 and presence of IgAN. Patient subgroup analysis revealed that that the presence of nephrotic range proteinuria (>40 mg/m/h) was associated with rs6334 of NTRK1 and rs11030104, rs7103411, rs7103873, and rs6484320 of BDNF. Significant genotype differences were observed in podocyte foot process effacement for rs1187321 and rs1187323 of NTRK2. Furthermore, some SNPs showed significantly different genotype distribution between patients with or without pathologically advanced disease markers, specifically in rs6334 of NTRK1. Our results suggest that SNPs of NTs and NTRs are associated with susceptibility, pathological advancement, podocyte foot process effacement, and development of proteinuria in childhood IgAN.

Impaired nerve growth factor homeostasis in patients with bipolar disorder

OBJECTIVE

Neuro-trophins are critically involved in neuro-plasticity, the impairment of which is a major role-player in bipolar disorder (BD), and their altered levels have been recently advocated in the patho-physiology of this affective malady. The aim of this study, therefore, was to evaluate the plasma levels of nerve growth factor (NGF) in BD patients in comparison with control subjects.

METHODS

Forty-nine BD type-I individuals (30 in mania and 19 in euthymia) and 36 healthy controls were assessed by Mini-plus, Young mania and Hamilton depression rating scales. NGF levels were detected by ELISA.

RESULTS

Plasma NGF concentrations were decreased in BD patients when compared to that seen with controls. BD individuals in mania had lower NGF levels than euthymic patients or controls. NGF levels were negatively correlated with the severity of mania.

CONCLUSIONS

This is the first study to evaluate NGF levels in BD patients, providing further support to the hypothesis of impaired neuro-plasticity in BD. These data also suggest that NGF measurement could be used for the biological marker for manic state.

Neurotrophins in lung health and disease

Neurotrophins (NTs) are a family of growth factors that are well-known in the nervous system. There is increasing recognition that NTs (nerve growth factor, brain-derived neurotrophic factor and NT3) and their receptors (high-affinity TrkA, TrkB and TrkC, and low-affinity p75NTR) are expressed in lung components including the nasal and bronchial epithelium, smooth muscle, nerves and immune cells. NT signaling may be important in normal lung development, developmental lung disease, allergy and inflammation (e.g., rhinitis, asthma), lung fibrosis and even lung cancer. In this review, we describe the current status of our understanding of NT signaling in the lung, with hopes of using aspects of the NT signaling pathway in the diagnosis and therapy of lung diseases.

Changes in plasma levels of BDNF and NGF reveal a gender-selective vulnerability to early adversity in rhesus macaques

Early stressful events can increase vulnerability for psychopathology, although knowledge on the effectors is still limited. Here we tested the hypothesis that peripheral levels of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF), which are involved in the response to stress and in the pathophysiology of anxiety and depression, might be affected in a non-human primate model of adverse rearing. Males and females rhesus macaques reared with their mothers (MR) or in peer-only groups (PR) were used as experimental subjects. BDNF, NGF, adrenocorticotropic hormone (ACTH), cortisol and growth hormone (GH) were determined at baseline on postnatal days (PND) 14, 30 and 60 by means of specific ELISA and RIA procedures. In addition, behavior was assessed on PND 7, 14, 21, 30 (Brazelton test) and 60 (home cage observation). Data indicate gender differences in basal levels of BDNF throughout development. Peer-rearing increased significantly BDNF levels only in females. In addition, while all peer-reared subjects showed high levels of stereotypies and self-directed behaviors, behavioral passivity was selectively increased in females. By contrast, NGF levels were increased in response to peer-rearing only in males, and correlated positively with other "classic" endocrine responses to stress, such as cortisol and GH. Our data identify BDNF and NGF as neuroendocrine markers underlying differential responses to maternal deprivation in males and females rhesus macaques. The selective changes in BDNF levels in females could help explain the greater vulnerability to mood disorders of this gender reported in humans.

New aspects concerning ulcerative colitis and colonic carcinoma: analysis of levels of neuropeptides, neurotrophins, and TNFalpha/TNF receptor in plasma and mucosa in parallel with histological evaluation of the intestine

BACKGROUND

The levels of neuropeptides, neurotrophins, and TNFalpha (TNFalpha)/TNF receptor in plasma and mucosa for patients with ulcerative colitis (UC) and colonic carcinoma, and concerning plasma also for healthy controls, were examined. Moreover, the relationships between the different substances and the influence of mucosal derangement on the levels were analyzed.

METHODS

The levels of VIP, SP, CGRP, BDNF, NGF, and TNFalpha/TNF receptor 1 were measured using ELISA/EIA.

RESULTS

Patients with UC demonstrated the highest levels of all analyzed substances in plasma, with the exception of BDNF. However, there were differences within the UC group, patients treated with corticosteroids, and/or nonsteroid antiinflammatory/immunosuppressive treatment having higher plasma levels than those not given these treatments. Patients with colonic carcinoma showed higher SP and TNF receptor 1 levels in plasma compared to healthy controls. Concerning mucosa, the levels of almost all analyzed substances were elevated for patients with UC compared to noncancerous mucosa of colonic carcinoma patients. There were correlations between many of the substances in both plasma and mucosa, especially concerning the 3 neuropeptides examined. There were also marked associations with mucosa derangement.

CONCLUSIONS

Via analysis of correlations for the respective patients and via comparisons between the different patient groups, new and original information was obtained. Interestingly, the degree of mucosal affection was markedly correlated with tissue levels of the substances and the treatments were found to be of importance concerning plasma but not tissue levels of these. Combined plasma analysis of neuropeptides, neurotrophins, and TNF receptor 1 may help to distinguish UC and colonic carcinoma patients.

Early life stress as a risk factor for mental health: role of neurotrophins from rodents to non-human primates

Early adverse events can enhance stress responsiveness and lead to greater susceptibility for psychopathology at adulthood. The epigenetic factors involved in transducing specific features of the rearing environment into stable changes in brain and behavioural plasticity have only begun to be elucidated. Neurotrophic factors, such as nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF), are affected by stress and play a major role in brain development and in the trophism of specific neuronal networks involved in cognitive function and in mood disorders. In addition to the central nervous system, these effectors are produced by peripheral tissues, thus being in a position to integrate the response to external challenges. In this paper we will review data, obtained from animal models, indicating that early maternal deprivation stress can affect neurotrophin levels. Maladaptive or repeated activation of NGF and BDNF, early during postnatal life, may influence stress sensitivity at adulthood and increase vulnerability for stress-related psychopathology.

BDNF in RA: downregulated in plasma following anti-TNF treatment but no correlation with inflammatory parameters

The involvement of brain-derived neurotrophic factor (BDNF) in rheumatoid arthritis (RA) is largely unknown. The distribution of BDNF and its associated receptors, TrkB and p75, in the synovial tissue of patients with RA was examined and contrasted with that in patients with osteoarthritis (OA). Additionally, levels of BDNF in both synovial tissue and synovial fluid were measured. Furthermore, the effects of anti-tumour necrosis factor (anti-TNF; infliximab) treatment on BDNF levels in the plasma of RA patients were analysed. Cells in the synovium showed immunoreactivity for BDNF and BDNF-, p75- and TrkB-receptor immunoreactions were seen in nerve fibres of nerve fascicles and in association with sensory corpuscles. The levels of BDNF in synovial tissue were not correlated with the number of inflammatory cells observed microscopically or with levels of TNFalpha. Nor did the BDNF levels in synovial fluid correlate with erythrocyte sedimentation rate (ESR) or white blood cell counts. Anti-TNF treatment lead to a decrease in plasma levels of BDNF 14 weeks after the initiation of anti-TNF therapy, i.e., 8 weeks after the last infusion. Higher levels of BDNF were observed in RA patients at baseline compared with those for healthy individuals. However, the levels of BDNF in plasma of patients treated with anti-TNF did not correlate with the changes in ESR or a disease activity score. The clinical significance of this study is that anti-TNF treatment influences plasma levels of BDNF although there was no evidence that BDNF levels correlate with inflammatory parameters in either infliximab-treated or non-infliximab-treated patients with RA. Instead it is likely that sources other than inflammatory cells, including nerve structures, are important sources of BDNF and that the effects of anti-TNF treatment on BDNF levels may be related to effects on circulating and various local cells and/or BDNF-containing neurons.

Expression of the heparin-binding growth factor midkine in the cerebrospinal fluid of patients with neurological disorders

OBJECTIVE

This study was to clarify the roles of midkine (MK) in the brain.

METHODS

We determined cerebrospinal fluid MK levels in patients with neurological disorders by enzyme-linked immunoassay and immunostained autopsied brain samples in patients with meningitis.

RESULTS

MK levels were 0.37+/-0.21 ng/ml in controls (n=46, mean +/- S.D.), 0.67+/-0.19 ng/ml in patients with cerebral infarction (n=8), 1.78+/-1.32 ng/ml in patients with meningitis (n=25; ANOVA and post-hoc Fisher's PLSD test, p<0.0001), 0.31+/-0.25 ng/ml in patients with human T-lymphotrophic virus type I-associated myelopathy/tropical spastic paraparesis (n=29), and 0.42+/-0.17 ng/ml in patients with amyotrophic lateral sclerosis (n=8). The regression equations were Y=0.005X+0.498 (Y, CSF MK level; X, cell number) and Y=0.007X+0.326 (Y, MK level; X, protein level) for all CSF samples. Autopsy brain samples from patients with meningitis expressed MK weakly in mononuclear cells on immunohistochemical examination. Western blot and polymerase chain reaction analyses showed that leukocytes were MK positive. CSF MK levels were not high in patients with cerebral infarction but were increased in patients with meningitis. CSF MK levels were high in normal controls, compared to those of other cytokines. MK was expressed in choroid plexus of normal brain and released there.

CONCLUSION

Our findings suggested that MK may maintain normal adult brain as a neurotrophic factor, and that MK may be released from leucocytes in brain of patients with meningitis as an immunological mediator.

Body length and head growth in the first year of life in autism

Data on the growth of the head in the first year of life in children with autism spectrum disorders are inconsistent. We measured head circumference and body length during the first year of life, and determined whether the head grew in proportion to body length. This is a case-control study nested in a population-based screening study of autism spectrum disorders. Longitudinal data for head circumference and body length of 53 children with autism spectrum disorders were compared with those of a control group and population norms, using univariate and multilevel statistical modeling. Growth of body length was accelerated, but growth of head circumference was normal in children with autism spectrum disorders compared with controls in the first year of life. The rate of macrocephaly we detected in the first year of life in our sample, 11.3%, fits within the 95% confidence intervals of macrocephaly rates in previous studies. Our findings suggest that autism spectrum disorder is due to a dysregulation of growth in general, rather than to a dysregulation of neuronal growth in the brain. It is unclear whether this early, disproportionate growth of children with autism spectrum disorders is specific to the disorder, and whether this growth could serve as a biomarker to delineate more homogeneous subtypes of autism spectrum disorders.

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.

Are Neurotrophins Important in Ulcerative Colitis?

Neurotrophins are known to have growth, survival-promoting, and healing effects. The importance of neurotrophins in ulcerative colitis (UC) is, however, unclear. Recent studies in our group revealed that an occurrence of marked changes in neurotrophin expression patterns was related to a worsening of the disease process. There was thus an upregulation for the lamina propria cells but a downregulation in nerve structures concerning neurotrophin expressions in severe UC. The observations show that changes in the neurotrophin system are a part of the disease process in UC and are of interest as treatments interfering with neurotrophin effects in other situations have been found to have trophic and healing effects.

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.

Study of expression patterns and levels of neurotrophins and neurotrophin receptors in ulcerative colitis

BACKGROUND

Neurotrophins may be involved in ulcerative colitis (UC). Yet, it is unclear whether if their effects should be blocked.

METHODS

In this study, the neurotrophins nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) and their receptors were examined by immunohistochemistry, ELISA, and RT-PCR.

RESULTS

BDNF immunoreaction was detected in nerve structures in particular, and NGF immunoreaction was detected in lamina propria cells. Cellular NGF immunoreaction was generally observed to be higher in the mucosa of UC patients than in the controls. In addition, UC patients demonstrated significantly higher p75 immunoreaction (P = 0.010) in lamina propria cells. The controls expressed significantly higher BDNF immunoreaction in the nerve structures than did UC patients (P = 0.000). However, the UC group showed marked interindividual variation in expression of neurotrophins and neurotrophin receptors. This included variation at the mRNA level for NGF. Differences with the controls were most pronounced in UC specimens demonstrating great infiltration of inflammatory cells and marked tissue derangement. Corticosteroid treatment seemed to affect neurotrophin production in lamina propria cells but not in nerve structures. These observations demonstrate that up-regulation and down-regulation of neurotrophins occur in different structural components in response to the disease process. Massive inflammation seemed to be correlated with decreased neurotrophin immunoreaction in nerve structures, but there was a tendency toward increased neurotrophin production in lamina propria cells.

CONCLUSIONS

Our study shows that UC patients are not a uniform group in their expression of neurotrophins, a fact that should be considered when discussing therapeutic interventions.