Brain-derived neurotrophic factor selectively enhances allergen-specific IgE production

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.

Brain-derived neurotrophic factor serum levels and genotype: association with depression during interferon-α treatment

Depression has been associated with inflammation, and inflammation may both influence and interact with growth factors such as brain-derived neurotrophic factor (BDNF). Both the functional Val66Met BDNF polymorphism (rs6265) and BDNF levels have been associated with depression. It is thus plausible that decreased BDNF could mediate and/or moderate cytokine-induced depression. We therefore prospectively employed the Beck Depression Inventory-II (BDI-II), the Hospital Anxiety and Depression Scale (HADS), and the Montgomery-Asberg Depression Rating Scale (MADRS) in 124 initially euthymic patients during treatment with interferon-alpha (IFN-α), assessing serum BDNF and rs6265. Using mixed-effect repeated measures, lower pretreatment BDNF was associated with higher depression symptoms during IFN-α treatment (F144,17.2=6.8; P<0.0001). However, although the Met allele was associated with lower BDNF levels (F1,83.0=5.0; P=0.03), it was only associated with increased MADRS scores (F4,8.9=20.3; P<0.001), and not the BDI-II or HADS. An exploratory comparison of individual BDI-II items indicated that the Met allele was associated with suicidal ideation, sadness, and worthlessness, but not neurovegetative symptoms. Conversely, the serotonin transporter promoter polymorphism (5-HTTLPR) short allele was associated with neurovegetative symptoms such as insomnia, poor appetite and fatigue, but not sadness, worthlessness, or suicidal ideation. IFN-α therapy further lowered BDNF serum levels (F4,37.7=5.0; P=0.003), but this decrease occurred regardless of depression development. The findings thus do not support the hypothesis that decreasing BDNF is the primary pathway by which IFN-α worsens depression. Nonetheless, the results support the hypothesis that BDNF levels influence resiliency against developing inflammatory cytokine-associated depression, and specifically to a subset of symptoms distinct from those influenced by 5-HTTLPR.

Mucosal expression of nerve growth factor and brain-derived neurotrophic factor in chronic rhinosinusitis

BACKGROUND

Allergic rhinitis (AR) is characterized in part by hyperresponsiveness to nonspecific stimuli, a phenomenon that reflects the fundamental role of nasal neural pathways in chronic airway inflammation. Neurotrophins may serve pivotal roles in mediating hyperresponsiveness in allergic airway disease, although the role of such neurogenic mediators in chronic rhinosinusitis (CRS) is not well understood. This study was designed to examine the expression of two potent neurotrophins, nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF), in CRS.

METHODS

Inferior turbinate and sinus mucosa were obtained from CRS patients with and without nasal polyps (NPs) and from nonallergic controls. Enzyme-linked immunosorbent assay was used for quantitative determination of tissue concentrations of NGF and BDNF.

RESULTS

Ninety-four tissue samples from 48 patients were included. Mean concentration of NGF in sinus mucosa was significantly higher in CRS than controls. CRS without NPs was associated with a 60% increase in sinus NGF over controls (p < 0.05), and CRS with NPs was associated with a 140% increase (p < 0.05). Mean sinus NGF concentration was significantly elevated in allergic subjects compared with controls (p < 0.01). A similar trend was noted in subjects with nonallergic CRS, although this did not reach significance. Mean BDNF concentration was decreased in CRS compared with controls, with the most significant decrease in patients with polyps (p < 0.05). Mean turbinate concentration of both NGF and BDNF were similar in controls and CRS.

CONCLUSION

Increased expression of NGF may contribute to neural hyperresponsiveness in CRS sinus mucosa, particularly those patients with NP and/or allergies. BDNF expression is decreased in CRS sinus mucosa. Alterations in neurogenic inflammation may contribute to the pathophysiology of CRS and provide alternative therapeutic targets.

Brain-derived neurotrophic factor gene polymorphisms and serum levels in Chinese atopic dermatitis patients

BACKGROUND

Brain-derived neurotrophic factor (BDNF) plays an important role in the pathogenesis of atopic dermatitis (AD). Whether BDNF gene polymorphisms are associated with Chinese AD remains totally unknown.

OBJECTIVE

The aim is to determine if BDNF gene C270T and G196A polymorphisms are associated with Chinese AD, and analyse the clinical relevance of BDNF gene polymorphisms and BDNF serum levels. Methods We conducted a case-control association analysis (160 patients and 169 controls) in Northern Chinese subjects. Genotyping was performed by restriction fragment length polymorphism, and serum levels of BDNF were measured using enzyme-linked immunosorbent assay.

RESULTS

For C270T, there were significant differences in C/T genotype distribution (P = 0.003) and T allele frequencies (P = 0.004) between AD patients and controls in the whole dataset. Higher C/T genotype frequencies were found in male AD (10.6% vs. 1.1%, P = 0.018) and in intrinsic AD (IAD; 15.79% vs. 2.91%, P = 0.008). No association between G196A polymorphism and AD was observed in the whole cohort, while A allele was much more frequent in AD patients with atopy in first-degree relatives (65.8% vs. 34.2%, P = 0.038). Serum BDNF levels were correlated with IAD severity as measured by Scoring Atopic Dermatitis index (r = 0.576, P < 0.001).

CONCLUSION

T allele in C270T may be a risk factor for AD, especially in IAD and male AD. A allele in G196A may be a risk factor in AD patients with atopy in first-degree relatives. Serum BDNF levels were correlated with the severity of IAD.

Clinical grading of atopic keratoconjunctivitis

PURPOSE OF REVIEW

Atopic keratoconjunctivitis (AKC), the most severe and chronic form of ocular surface allergy-related disorder, is the ocular surface complication that some atopic dermatitis patients can suffer. Its wide range of severity, from mild and occasional problems to persistent and intense inflammation, makes it difficult to appropriately select uniform patients for clinical studies. This article proposes a new classification system for AKC based on clinical severity.

RECENT FINDINGS

Recent reports on AKC have contributed to a better understanding of the pathogenesis and clinical manifestations, and are offering new therapeutic candidates for AKC. No reports, however, have been found that address a classification of this disease.

SUMMARY

A new definition and classification for AKC is presented by this review, based on clinical severity, grading the main symptoms and signs. It intends to serve as a first forum of discussion among clinicians and other scientists working in the field of ocular surface inflammation. The final intention is to have a common language helping develop efficient clinical trials leading to successful approval of new therapeutic compounds for this blinding ocular surface condition.

Differential regulation of neurotrophin expression in human bronchial smooth muscle cells

Background

Human bronchial smooth muscle cells (HBSMC) may regulate airway inflammation by secreting cytokines, chemokines and growth factors. The neurotrophins, including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3), have been shown to be elevated during airway inflammation and evoke airway hyperresponsiveness. We studied if HBSMC may be a source of NGF, BDNF and NT-3, and if so, how inflammatory cytokines may influence their production.

Methods

Basal and cytokine (IL-1β, IFN-γ, IL-4)-stimulated neurotrophin expression in HBSMC cultured in vitro was quantified. The mRNA expression was quantified by real-time RT-PCR and the protein secretion into the cell culture medium by ELISA.

Results

We observed a constitutive NGF, BDNF and NT-3 expression. IL-1β stimulated a transient increase of NGF, while the increase of BDNF had a later onset and was more sustained. COX-inhibitors (indomethacin and NS-398) markedly decreased IL-1β-stimulated secretion of BDNF, but not IL-1β-stimulated NGF secretion. IFN-γ increased NGF expression, down-regulated BDNF expression and synergistically enhanced IL-1β-stimulated NGF expression. In contrast, IL-4 had no effect on basal NGF and BDNF expression, but decreased IL-1β-stimulated NGF expression. NT-3 was not altered by the tested cytokines.

Conclusion

Taken together, our data indicate that, in addition to the contractile capacity, HBSMC can express NGF, BDNF and NT-3. The expression of these neurotrophins may be differently regulated by inflammatory cytokines, suggesting a dynamic interplay that might have a potential role in airway inflammation.