Increased Nerve Growth Factor Production Research Articles

Leptin receptor+ cells promote bone marrow innervation and regeneration by synthesizing nerve growth factor

The bone marrow contains peripheral nerves that promote haematopoietic regeneration after irradiation or chemotherapy (myeloablation), but little is known about how this is regulated. Here we found that nerve growth factor (NGF) produced by leptin receptor-expressing (LepR+) stromal cells is required to maintain nerve fibres in adult bone marrow. In nerveless bone marrow, steady-state haematopoiesis was normal but haematopoietic and vascular regeneration were impaired after myeloablation. LepR+ cells, and the adipocytes they gave rise to, increased NGF production after myeloablation, promoting nerve sprouting in the bone marrow and haematopoietic and vascular regeneration. Nerves promoted regeneration by activating β2 and β3 adrenergic receptor signalling in LepR+ cells, and potentially in adipocytes, increasing their production of multiple haematopoietic and vascular regeneration growth factors. Peripheral nerves and LepR+ cells thus promote bone marrow regeneration through a reciprocal relationship in which LepR+ cells sustain nerves by synthesizing NGF and nerves increase regeneration by promoting the production of growth factors by LepR+ cells.

Singlet oxygen -derived nerve growth factor exacerbates airway hyperresponsiveness in a mouse model of asthma with mixed inflammation

BackgroundRefractory asthma, which is caused by several factors including neutrophil infiltration is a serious complication of bronchial asthma. We previously reported that nerve growth factor (NGF) is involved in AHR. NGF-derived induction of hyperalgesia is dependent on neutrophils; however, this relationship remains unclear in respiratory disease. In this study, we examined the roles of neutrophils and NGF in refractory asthma. MethodsUsing intranasal house dust mite sensitization, we established a mouse model of asthma with mixed inflammation (Mix-in). AHR, NGF production and hyperinnervation of the lungs were examined with or without different inhibitory treatments. The levels of the singlet oxygen markers, 10- and 12-(Z,E)-hydroxyoctadecadienoic acids (HODE) in the lungs, were measured by liquid chromatography-tandem mass spectrometry. An in vitro experiment was also performed to evaluate the direct effect of singlet oxygen on NGF production. ResultsNGF production and hyperinnervation were higher in Mix-in mice than in conventional eosinophilic-asthmatic mice and were positively correlated with AHR. Asthmatic parameters were inhibited by NGF neutralizing Abs and myeloperoxidase (MPO) inhibition. The 10- and 12-(Z,E)-HODEs levels were increased in the lungs and were positively correlated with MPO activity and NGF production. NGF was produced by bronchial epithelial cells in vitro upon stimulation with singlet oxygen. ConclusionsOur findings suggest that neutrophil MPO-derived singlet oxygen induces increased NGF production, leading to AHR and 10- and 12-(Z,E)-HODEs production. These findings may help to develop new therapies targeting this mechanism and to establish a new biomarker for non-type 2 and refractory asthma.

Neurotrophic isoindolinones from the fruiting bodies of Hericium erinaceus

Four compounds, hericerin (1), isohericerinol A (2), N-de-phenylethyl isohericerin (3) and corallocin A (4) were isolated from the fruiting bodies of Hericium erinaceus, a lion’s mane mushroom (Hericiaceae). Among them, isohericerinol A (2) was newly reported in nature. Further investigation of the neurotrophic effect of isolated compounds demonstrated that isohericerinol A (2) strongly increased the nerve growth factor (NGF) production in C6 glioma cells followed by corallocin A (4) and hericerin (1). Increased NGF production by these compounds promoted the neurite outgrowth in N2a neuronal cells. Western blot analysis also showed the increased protein expression of NGF, brain-derived neurotrophic factor (BDNF) and synaptophysin (SYP) in C6-N2a cells. Taken together, our present study characterized the neurotrophic constituents of H. erinaceus, which may support the potential use of memory improvement.

Human Adenomyosis Endometrium Stromal Cells Secreting More Nerve Growth Factor: Impact and Effect.

Abnormal expression of nerve growth factor (NGF) was found in adenomyosis (AM). We collected AM foci from patients and eutopic endometrium from non-AM controls. Endometrium stromal cells (ESCs) were cultured. Different levels of 17β-estradiol, tumor necrosis factor (TNF), CoCl2, and H2O2 were added to the culture system separately, then the expression level of NGF in ESCs was detected. After adding different levels of NGF, the proliferation and apoptosis of ESCs and aromatase expression were detected. We found that 17β-estradiol promoted NGF production in AM ESCs but not in control ESCs; TNF promoted NGF production in both AM and control ESCs; and CoCl2 inhibited NGF production in control ESCs, but had no effect in AM ESCs. Nerve growth factor promoted the proliferation and synthesis of aromatase in AM ESCs. In conclusion, locally increased estrogen levels and inflammation may cause increased NGF production in the uterus of patients with AM. Nerve growth factor stimulated the proliferation and increased aromatase expression of ESCs from AM foci, suggesting NGF might contribute to the pathology and etiology of AM.

Increased Nerve Growth Factor Serum Levels in Top Athletes

The nerve growth factor (NGF) is the main neurotrophin, which, besides being an important growth factor for nerves, plays an important role as a mediator of inflammation. Nerve growth factor has been shown to increase in relation to stress stimuli and in allergic diseases in humans as well as after physical exercise in animal models. This study aims at evaluating NGF serum levels in top athletes, a population sample in which allergic and neuro-immune diseases are reported with a significantly increased prevalence. Observational, cross-sectional, multicenter study. Institutional, tertiary care. Ninety-six Italian pre-Olympic athletes (44 allergic and 52 nonallergic) and 49 matched controls selected within the Italian National Olympic delegation (n = 435). Nerve growth factor serum levels determined through an enzyme-linked immunosorbent assay. Parametric or nonparametric tests were used for comparing NGF serum levels among different study groups depending on value distributions. Nerve growth factor serum levels were significantly higher in athletes than in controls independently from the presence of allergy. Nerve growth factor mean values were 368.3 ± 776.3 pg/mL in the sample of athletes and 174.1 ± 483.7 pg/mL in the control group (P < 0.001). This is the first study showing that intense and prolonged physical exercise is associated with an increase of NGF serum levels in athletes. Whether the increased NGF production might be linked to the prevalent Th2 response observed in allergic diseases and after physical exercise and whether it might be related to the patophysiology of neuro-immune disorders as such amyotrophic lateral sclerosis, reported with a higher prevalence in athletes, should deserve further investigations.

Interleukin 1-beta upregulates brain-derived neurotrophic factor, neurotrophin 3 and neuropilin 2 gene expression and NGF production in annulus cells

The relationship between disc cells, nerves and pain production in the intervertebral disc is poorly understood. Neurotrophins, signaling molecules involved in the survival, differentiation and migration of neurons, and neurite outgrowth, are expressed in non-neuronal tissues including the disc. We hypothesized that three-dimensional exposure of human disc cells to the proinflammatory cytokine IL-1ß in vitro would elevate neurotrophin gene expression levels and production of nerve growth factor (NGF). Cells isolated from Thompson grade III and IV discs were cultured for 14 days under control conditions or with addition of 102 pM IL-1ß; mRNA was isolated and conditioned media assayed for NGF content. IL-1ß exposure in three-dimensional culture significantly increased expression of neurotrophin 3, brain-derived neurotrophic factor, and neuropilin 2 compared to controls. IL-1ß-exposed cells showed significantly increased NGF production compared to controls. Findings support our hypothesis, expand previous data concerning expression of neurotrophins, and provide the first documented expression of neurotrophin 3 and neuropilin 2. Our results have direct translational relevance, because they address the primary clinical issue of low back pain and open the possibility of novel analgesic therapies using specific small-molecular antagonists to neurotrophins.

Dysregulation of astrocyte–motoneuron cross-talk in mutant superoxide dismutase 1-related amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis is a neurodegenerative disease in which death of motoneurons leads to progressive failure of the neuromuscular system resulting in death frequently within 2-3 years of symptom onset. Focal onset and propagation of the disease symptoms to contiguous motoneuron groups is a striking feature of the human disease progression. Recent work, using mutant superoxide dismutase 1 murine models and in vitro culture systems has indicated that astrocytes are likely to contribute to the propagation of motoneuron injury and disease progression. However, the basis of this astrocyte toxicity and/or failure of motoneuron support has remained uncertain. Using a combination of in vivo and in vitro model systems of superoxide dismutase 1-related amyotrophic lateral sclerosis, linked back to human biosamples, we set out to elucidate how astrocyte properties change in the presence of mutant superoxide dismutase 1 to contribute to motoneuron injury. Gene expression profiling of spinal cord astrocytes from presymptomatic transgenic mice expressing mutant superoxide dismutase 1 revealed two striking changes. First, there was evidence of metabolic dysregulation and, in particular, impairment of the astrocyte lactate efflux transporter, with resultant decrease of spinal cord lactate levels. Second, there was evidence of increased nerve growth factor production and dysregulation of the ratio of pro-nerve growth factor to mature nerve growth factor, favouring p75 receptor expression and activation by neighbouring motoneurons. Functional in vitro studies showed that astrocytes expressing mutant superoxide dismutase 1 are toxic to normal motoneurons. We provide evidence that reduced metabolic support from lactate release and activation of pro-nerve growth factor-p75 receptor signalling are key components of this toxicity. Preservation of motoneuron viability could be achieved by increasing lactate provision to motoneurons, depletion of increased pro-nerve growth factor levels or p75 receptor blockade. These findings are likely to be relevant to human amyotrophic lateral sclerosis, where we have demonstrated increased levels of pro-nerve growth factor in cerebrospinal fluid and increased expression of the p75 receptor by spinal motoneurons. Taken together, these data confirm that altered properties of astrocytes are likely to play a crucial role in the propagation of motoneuron injury in superoxide dismutase 1-related amyotrophic lateral sclerosis and indicate that manipulation of the energy supply to motoneurons as well as inhibition of p75 receptor signalling may represent valuable neuroprotective strategies.

Intraperitoneal injection of neuropeptide Y (NPY) alters neurotrophin rat hypothalamic levels: Implications for NPY potential role in stress-related disorders

Neuropeptide Y (NPY) is a 36-amino acid peptide which exerts several regulatory actions within peripheral and central nervous systems. Among NPY actions preclinical and clinical data have suggested that the anxiolytic and antidepressant actions of NPY may be related to its antagonist action on the hypothalamic–pituitary–adrenal (HPA) axis. The neurotrophins brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) are proteins involved in the growth, survival and function of neurons. In addition to this, a possible role of neurotrophins, particularly BDNF, in HPA axis hyperactivation has been proposed. To characterize the effect of NPY on the production of neurotrophins in the hypothalamus we exposed young adult rats to NPY intraperitoneal administration for three consecutive days and then evaluated BDNF and NGF synthesis in this brain region. We found that NPY treatment decreased BDNF and increased NGF production in the hypothalamus. Given the role of neurotrophins in the hypothalamus, these findings, although preliminary, provide evidence for a role of NPY as inhibitor of HPA axis and support the idea that NPY might be involved in pathologies characterized by HPA axis dysfunctions.

Inflammatory Cytokine Tumor Necrosis Factor-α Enhances Nerve Growth Factor Production in Human Keratinocytes, HaCaT Cells

The skin lesions of inflammatory skin diseases (e.g., atopic dermatitis or psoriasis) accompany infiltration of inflammatory cells like macrophages, where abnormal sensory innervations and elevation of nerve growth factor (NGF) level are observed. It is thought that increased NGF mediates the abnormal innervations and this may cause the hypersensitivity of the skin. However, the mechanism of this increased NGF production in the skin is still unknown. Here, we show that tumor necrosis factor (TNF)-α, but not interferon-γ or interleukin-6, enhanced the NGF production in human keratinocytes. The enhanced NGF production was abolished by both Raf-1 kinase and MEK inhibitors, whereas specific inhibitors of p38 mitogen–activated protein kinase and c-Jun N-terminal kinase did not. The extracellular signal–regulated kinase (ERK) phosphorylation and expression of NGF mRNA were accelerated by TNF-α treatment. Furthermore, serum was necessary for the NGF production and epidermal growth factor could substitute for serum in the effect on NGF secretion. These results indicate that TNF-α enhances NGF production via the Raf-1 / MEK / ERK pathway in human keratinocytes, suggesting that regulating TNF-α is a therapeutic target to control NGF production and subsequent sensory innervations.

Increased NGF During Lung Ischemia and Reperfusion and Its Effect on MIP‐2 Production by Alveolar Macrophages

To assess its role as a potential inflammatory mediator, nerve growth factor (NGF) levels were measured during lung ischemia and reperfusion (I/R). Long Evans rats underwent 90 minutes of unilateral left lung ischemia and four hours of reperfusion. Sham animals underwent an identical surgical procedure without ischemia. During reperfusion, NGF levels significantly increased in the ischemic and nonischemic contralateral lung. Alveolar macrophages are activated by I/R and respond by producing chemokines and other inflammatory mediators; therefore, the ability of NGF to affect MIP-2 production was examined in these cells as they express NGF receptors. Treatment of alveolar macrophage cell cultures with beta-NGF in the presence of LPS increased MIP-2 production. NGF significantly enhanced LPS-induced MIP-2 production after 4 hours (50%) and 24 hours (32%) although NGF alone had no effect on MIP-2 production. Cell cultures pretreated with NGF prior to LPS stimulation produced more MIP-2. To determine whether this increase in MIP-2 production might be due to altered ERK phosphorylation, cells were serum-starved for 1 hour and then treated with NGF in the absence and presence of LPS. After 30 minutes, maximal ERK phosphorylation was observed in cultures treated with both NGF and LPS in contrast to LPS alone where ERK phosphorylation peaked later at 60 minutes. These data suggest that increased NGF production during lung I/R may potentiate macrophage MIP-2 production by enhancing ERK activation. This work is supported by NIH grants GM-61656, GM-29507 and HL-31963.

Effects of Anti-Nerve Growth Factor Antibody on Symptoms in the NC/Nga Mouse, an Atopic Dermatitis Model

Nerve growth factor (NGF) is an important substance in the skin, where it can modulate nerve maintenance and repair. However, the direct link between NGF and pruritic disease such as atopic dermatitis is not yet fully understood. To determine whether NGF plays a major role in atopic dermatitis and in the development or maintenance of skin lesions, we performed a study using NC/Nga mice and compared mice with and without skin lesions. Our examinations of the NC/Nga mice sought to detect nerve fibers in the epidermis, measured serum and skin NGF content, and observed skin NGF by immunohistochemistry staining. We also examined the effects of anti-NGF antibody on dermatitis symptoms in NC/Nga mice. In these mice, nerve fibers were significantly increased in the epidermis of lesioned skin, and the NGF content of the serum and skin was significantly elevated. Anti-NGF antibodies significantly inhibited the development and proliferation of skin lesions and epidermal innervation and significantly inhibited any growth in scratching but did not ameliorate scratching already developed. Our findings suggest that NGF plays important roles in the pathogenesis of atopic dermatitis-like skin lesions and that inhibiting the physiological effects of NGF or suppressing increased NGF production may prevent or even moderate the symptoms of atopic dermatitis.

Mechanisms of Increased NGF Production in Vascular Smooth Muscle of the Spontaneously Hypertensive Rat

The spontaneously hypertensive rat (SHR) was developed as a genetic model of essential hypertension.In vivoandin vitroevidence demonstrates that vascular smooth muscle cells (VSMCs) from the SHR produce more nerve growth factor (NGF) than the normotensive Wistar-Kyoto (WKY) control strain. This increased NGF production is accompanied by excessive innervation of target tissues in the SHR. In the present study, a sensitive, competitive, quantitative, reverse-transcriptase polymerase chain reaction (C Q RT-PCR) assay is characterized and used to analyze levels of NGF mRNA in cultured VSMCs derived from the SHR and WKY strains as well as bladder tissue. Differences in NGF secretion rates between SHR and WKY VSMCs were partially due to an increased stability of NGF mRNA in SHR VSMCs. Following treatment with platelet-derived growth factor (PDGF) and transforming growth factor-β (TGF-β1) to elevate NGF production, the half-life of the NGF mRNA was 104.5 ± 18.0 min in SHR VSMCs, compared to only 36.5 ± 11.6 min in WKY VSMCs. Sequence analysis of the 3′ untranslated region (UTR) revealed no strain differences incis-acting sequences potentially involved in determining mRNA stability. Thus, it seems unlikely to be a 3′UTR mutation that prolongs mRNA lifetime. Rather, differential regulation of an RNA-binding protein may play a role in the abnormal NGF mRNA stability in SHR VSMCs. SHR VSMCs also demonstrate an increased translational efficiency of NGF protein; more NGF protein is synthesized per unit of NGF mRNA. The use of a C Q RT-PCR assay has allowed the determination that abnormal NGF mRNA stabilization as well as altered translational efficiency may contribute to excess NGF synthesis and progressive hypertension in the SHR.

Increased NGF mRNA expression in denervated rat skin

Using a coupled reverse transcription and competitive polymerase chain reaction protocol, we have measured Nerve Growth Factor (NGF) mRNA expression in adult rat skin following its denervation. By 2-4 days, levels of NGF mRNA were increased approximately 5-10 fold over levels in innervated skin, remaining increased for up to at least 2 weeks. In situ hybridization carried out on skin samples revealed that the NGF message was expressed not only in the distal nerve pathways but also in non-nerve associated cells, such as dermal fibroblasts, and in the basal epidermal layer. Denervated skin evokes a NGF-dependent collateral sprouting from neighbouring intact sensory axons. The new findings indicate that an increased NGF production is associated with the increased availability of NGF in such skin, and that cutaneous nerves have a role in regulating this NGF production.

Nerve growth factor synthesis in cultured rat iris: Modulation by endogenous transmitter substances

Organ cultures of rat iris show a characteristic change in the levels of both nerve growth factor (NGF) and its mRNA: a rapid but transient initial increase is followed by a smaller but persistently elevated NGF synthesis. This time course may be influenced by release of a factor(s) from degenerating nerve terminals and/or by the lack of some factor(s) repressing NGF synthesis in vivo. We therefore analyzed the influence of biogenic amine transmitter substances and putative neuropeptides on this elevation of NGF synthesis in cultured iris. The marked increase of NGF synthesis seen initially in culture was not completely mimicked by any of the substances tested. A specific increase in NGF production up to 150 % of control was observed only with cGMP. We also obtained some evidence that reaction to trauma following the culture procedure could enhance NGF production: cutting of hides into small pieces increased NGF production in culture up to 250% of control and, vice versa, treatment with 1 μ M dexamethasone decreased NGF production to about 60 % of control. However, the sympathetic neurotransmitter norepinephrine (NE) decreased both NGF and its mRNA levels specifically in a dose-dependent manner (0.01-1 m M) to a minimum of about 25% of control. In situ hybridization with mRNA NGF-specific probes showed that in cultures of dissociated iris cells all cells were capable of expressing mRNA NGF, but that 0.1 m M NE preferentially decreased expression of mRNA NGF in smooth muscle cells. Thus, our results indicate that the sympathetic transmitter NE is capable of downregulating NGF synthesis in the target cells of sympathetic neurons.