Nerve growth factor: a neurokine orchestrating neuroimmune-endocrine functions

Pathophysiology of Pain and Mechanisms of Neuromodulation: A Narrative Review (A Neuron Project)

Pain serves as a vital innate defense mechanism that can significantly impact an individual's quality of life. Understanding the physiological effects of pain well plays an important role in developing novel pain treatments. Nociceptor neurons play a key role in pain and inflammation. Interactions between nociceptors and the immune system occur both at the site of injury and within the central nervous system. Modulating chemical mediators and nociceptor activity offers promising new approaches to pain management. Essentially, the sensory nervous system is essential for modulating the body's protective response, making it critical to understand these interactions to discover new pain treatment strategies. New innovations in neuromodulation have led to alternatives to opioids individuals with chronic pain with consequent improvement in disease-based treatment and nerve targeting. New neural targets from cellular and structural perspectives have revolutionized the field of neuromodulation. This narrative review aims to elucidate the mechanisms of pain transmission and processing, examine the characteristics and properties of nociceptors, and explore how the immune system influences pain perception. It further provides an updated overview of the physiology of pain and neuromodulatory mechanisms essential for managing acute and chronic pain. We assess the current understanding of different pain types, focusing on key molecules involved in each type and their physiological effects. Additionally, we compare painful and painless neuropathies and discuss the neuroimmune interactions involved in pain manifestation.

Growth Factors to Enhance Nerve Regeneration: Approaching Clinical Translation

Following nerve injury, growth factors (GFs) are transiently upregulated in injured neurons, proliferating Schwann cells, and denervated muscle and skin. They act on these same cells and tissues to promote nerve regeneration and end-organ reinnervation. Consequently, much attention has been focused on developing GF-based therapeutics. A major barrier to clinical translation of GFs is their short half-life. To provide sustained GF treatment to the affected nerve, muscle, and skin in a safe and practical manner, engineered drug delivery systems are needed. This review highlights recent advancements in GF-based therapeutics and discusses the remaining hurdles for clinical translation.

Urine biomarkers for Alzheimer's disease: A new opportunity for wastewater-based epidemiology?

While Alzheimer's disease (AD) diagnosis, management, and care have become priorities for healthcare providers and researcher's worldwide due to rapid population aging, epidemiologic surveillance efforts are currently limited by costly, invasive diagnostic procedures, particularly in low to middle income countries (LMIC). In recent years, wastewater-based epidemiology (WBE) has emerged as a promising tool for public health assessment through detection and quantification of specific biomarkers in wastewater, but applications for non-infectious diseases such as AD remain limited. This early review seeks to summarize AD-related biomarkers and urine and other peripheral biofluids and discuss their potential integration to WBE platforms to guide the first prospective efforts in the field. Promising results have been reported in clinical settings, indicating the potential of amyloid β, tau, neural thread protein, long non-coding RNAs, oxidative stress markers and other dysregulated metabolites for AD diagnosis, but questions regarding their concentration and stability in wastewater and the correlation between clinical levels and sewage circulation must be addressed in future studies before comprehensive WBE systems can be developed.

Hybrid Electrically Conductive Hydrogels with Local Nerve Growth Factor Release Facilitate Peripheral Nerve Regeneration

It is challenging to treat peripheral nerve injury (PNI) clinically. As the gold standard for peripheral nerve repair, autologous nerve grafting remains a critical limitation, including tissue availability, donor-site morbidity, immune rejection, etc. Recently, conductive hydrogels (CHs) have shown potential applications in neural bioengineering due to their good conductivity, biocompatibility, and low immunogenicity. Herein, a hybrid electrically conductive hydrogel composed of acrylic acid derivatives, gelatin, and heparin with sustained nerve growth factor (NGF) release property was developed. The rat sciatic nerve injury (SNI) model (10 mm long segment defect) was used to investigate the efficacy of these hydrogel conduits in facilitating peripheral nerve repair. The results showed that the hydrogel conduits had excellent conductivity, mechanical properties, and biocompatibility. In addition, NGF immobilized in the hydrogel conduits had good sustained release characteristics. Finally, functional recovery and electrophysiological evaluations, together with histological analysis, indicated that the hydrogel conduits immobilizing NGF had superior effects on motor recovery, axon growth, and remyelination, thereby significantly accelerating the repairing of the sciatic nerve. This study demonstrated that hybrid electrically conductive hydrogels with local NGF release could be effectively used for PNI repair.

A Rare Skeletal Disorder, Fibrous Dysplasia: A Review of Its Pathogenesis and Therapeutic Prospects

Fibrous dysplasia (FD) is a rare, non-hereditary skeletal disorder characterized by its chronic course of non-neoplastic fibrous tissue buildup in place of healthy bone. A myriad of factors have been associated with its onset and progression. Perturbation of cell-cell signaling networks and response outputs leading to disrupted building blocks, incoherent multi-level organization, and loss of rigid structural motifs in mineralized tissues are factors that have been identified to participate in FD induction. In more recent years, novel insights into the unique biology of FD are transforming our understandings of its pathology, natural discourse of the disease, and treatment prospects. Herein, we built upon existing knowledge with recent findings to review clinical, etiologic, and histological features of FD and discussed known and potential mechanisms underlying FD manifestations. Subsequently, we ended on a note of optimism by highlighting emerging therapeutic approaches aimed at either halting or ameliorating disease progression.

NGF and Its Role in Immunoendocrine Communication during Metabolic Syndrome

Nerve growth factor (NGF) was the first neurotrophin described. This neurotrophin contributes to organogenesis by promoting sensory innervation and angiogenesis in the endocrine and immune systems. Neuronal and non-neuronal cells produce and secrete NGF, and several cell types throughout the body express the high-affinity neurotrophin receptor TrkA and the low-affinity receptor p75NTR. NGF is essential for glucose-stimulated insulin secretion and the complete development of pancreatic islets. Plus, this factor is involved in regulating lipolysis and thermogenesis in adipose tissue. Immune cells produce and respond to NGF, modulating their inflammatory phenotype and the secretion of cytokines, contributing to insulin resistance and metabolic homeostasis. This neurotrophin regulates the synthesis of gonadal steroid hormones, which ultimately participate in the metabolic homeostasis of other tissues. Therefore, we propose that this neurotrophin's imbalance in concentrations and signaling during metabolic syndrome contribute to its pathophysiology. In the present work, we describe the multiple roles of NGF in immunoendocrine organs that are important in metabolic homeostasis and related to the pathophysiology of metabolic syndrome.

Diagnostic and Management Strategies for Patients with Chronic Prostatitis and Chronic Pelvic Pain Syndrome

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a common and often heterogenous condition that can have severe consequences on patient quality of life. In this review, we describe the pathophysiology, diagnostic work-up, and treatment of patients with CP/CPPS incorporating the most recent literature. Studies have demonstrated that CP/CPPS involves a complex pathophysiology, including infectious, immunologic, neurologic, endocrinologic, and psychologic etiologies, with frequent intersections between the different entities. Despite robust research assessing a variety of therapeutics targeting these etiologies, clinical trials have failed to identify an empiric treatment strategy applicable specifically to older adult male patients with CP/CPPS. As such, it can be challenging to manage older male patients with this condition. The advent of clinical phenotyping of patients with CP/CPPS has led to advances in tailored management strategies. Monomodal therapy has been largely unsuccessful because of the unclear and complex etiology of CPPS. As a result, CP/CPPS therapy has transitioned to a multimodal approach, including both pharmacologic and non-pharmacologic therapies. The best studied pharmacologic therapies include antibiotics, alpha-blockers, anti-inflammatory and immunomodulatory agents, phytotherapies, phosphodiesterase inhibitors, hormonal agents, neuromodulatory agents, and antidepressants. The best studied non-pharmacological therapies include pelvic floor physical therapy, myofascial trigger point release, acupuncture and electroacupuncture, psychological support and biofeedback, and electrocorporeal shockwave therapy and local thermotherapy.

Neuro-Immune Modulation Effects of Sacral Nerve Stimulation for Visceral Hypersensitivity in Rats

Background: Visceral hypersensitivity (VH) is one of the underlying pathophysiologies of irritable bowel syndrome. Mast cell overactivation has been found to be one of the main causes of VH. We investigated the effects and mechanisms of actions of sacral nerve stimulation (SNS) on visceral pain in a rodent model of VH.

Methods: The VH was established by an intrarectal infusion of AA in 10-day-old pups. Rats were chronically implanted with electrodes for SNS and recording electromyogram (EMG) and electrocardiogram. The acute study was performed in 2-randomized sessions with SNS (14 Hz, 330 μs, 40% motor threshold or MT, 30 min) or sham-SNS. Later on, rats were randomized into SNS/sham-SNS groups and a chronic study was performed with 2 h-daily SNS or sham-SNS for 21 days. Visceromotor reflexes were assessed by abdominal EMG and withdrawal reflex (AWR). Colon tissues were collected to study colonic acetylcholine (ACh), the enteric neurons (ChAT, nNOS, and PGP9.5), mast cells activity [Tryptase, prostaglandins E2 (PGE2), and cyclooxygenases-2 (COX2)] and pain markers [nerve growth factor (NGF) and Sub-P].

Key Results: Sacral nerve stimulation significantly improved visceromotor reflexes assessed by the EMG and AWR, compared with sham-SNS. SNS normalized the protein expressions of ChAT and nNOS and regulated mast cells activity by downregulating Tryptase, COX2, and PGE2. Neonatal AA administration upregulated NGF and Sub-P; chronic SNS significantly decreased these pain biomarkers. Concurrently, chronic SNS increased ACh in colon tissues and vagal efferent activity.

Conclusions: Sacral nerve stimulation reduces VH in rats and this ameliorating effect might be attributed to the suppression of mast cell overactivation in the colon tissue via the modulation of autonomic nervous system functions.

Mouse nerve growth factor promotes neurological recovery in patients with acute intracerebral hemorrhage: A proof-of-concept study

BACKGROUND

ew drugs were confirmed to be effective in the treatments of neurological dysfunction caused by acute intracerebral hemorrhage (ICH). The present prospective clinical trial aims to evaluate the effect of mouse nerve growth factor (mNGF) on neurological function in patients with acute ICH.

METHODS

60 patients with acute spontaneous ICH were randomized to receive mNGF (mNGF group) and citicoline (control group) for 4 weeks within 24-72 h after onset, respectively. The primary outcome was difference in the neurological functional outcome at 3 months by the modified Rankin Scale score (mRS). The secondary outcomes were the changes in hematoma volume at 4 weeks and 3 months.

RESULTS

There were 55 patients receiving treatment (29 patients in the mNGF group, 26 patients in the control group). Among the patients, 46 patients finished the trial at 3 months; the odds of a shift towards death or dependence (mRS > 3) at 3 months in the mNGF group were lower than that in the control group with adjustment for age, sex, NIHSS at admission, and hematoma volume at admission (adjusted OR, 0.185; 95%CI, 0.059-0.582; P = 0.0039). The hematoma was gradually reduced in all 46 patients and absorbed after non-surgical treatment at 3 months. There was no significant difference in hematoma volume between the two groups. No serious adverse event was found.

CONCLUSIONS

The administration of mNGF and citicoline was well-tolerated in patients with acute ICH. mNGF was associated with improved neurological function and less disability in patients with ICH. Therefore, the quality of life of patients with ICH may be improved by mNGF.

TRIAL REGISTRATION

The trial is registered with the Chinese Clinical Trial Registry, number ChiCTR1800020258.

Sacral nerve stimulation ameliorates colonic barrier functions in a rodent model of colitis

BACKGROUND

The mucosal barrier damage is recognized as one of the key factors in the pathogenesis of colitis. While sacral nerve stimulation (SNS) was reported to have therapeutic potential for colitis, its mechanisms of actions on colonic permeability remained largely unknown.

METHODS

In this study, colitis was induced by intrarectal administration of TNBS in rats. Five days later, they were treated with SNS or sham-SNS for 10 days. The effects of SNS on colonic permeability were assessed by measuring the expression of tight-junction proteins involved in regulating permeability and the FITC-dextran test. The mechanism of actions of SNS was investigated by studying the function of the enteric nervous system (ENS) cells and analyzing the autonomic nervous system.

KEY RESULTS

SNS decreased the disease activity index, microscopic and macroscopic scores, myeloperoxidase activity, and pro-inflammatory cytokines (TNF-α, IL-6). SNS increased the expression of Zonula Occludens-1, Occludin, Claudin-1, and Junctional adhesion molecule-A in the colon tissue. The FITC-dextran test showed that the colonic permeability was lower with SCS than sham-SNS. SNS increased ChAT, pancreatic polypeptide, and GDNF and reduced norepinephrine NGF, sub-P, and mast cell overactivation in the colon tissue. Concurrently, SNS increased acetylcholine in colon tissues and elevated vagal efferent activity.

CONCLUSIONS & INFERENCES

SNS ameliorates colonic inflammation and enhances colonic barrier function with the proposed mechanisms involving the increase in parasympathetic activity and modulation of the activity of the ENS and immune system, including mast cells.

Dexmedetomidine Improves Locomotor Function and Alleviates Thermal Hyperalgesia Following Sciatic Nerve Crush Injury in Rats

PURPOSE

The effects of dexmedetomidine on locomotor function and thermal hyperalgesia in sciatic nerve crush injury (SNCI) were investigated using rats.

METHODS

After exposing the right sciatic nerve, the sciatic nerve was crushed for 1 minute by a surgical clip. One day after nerve injury, dexmedetomidine (5, 25, and 50 µg/kg) was directly applied to the injured sciatic nerve once a day for 14 days. Walking track analysis was used to assess locomotor function and plantar test was conducted to assess thermal pain sensitivity. Immunohistochemistry was performed to determine the expression of c-Fos in the ventrolateral periaqueductal gray (vlPAG) and paraventricular nucleus (PVN). Western blot was used to evaluate the expression level of nerve growth factor (NGF) and myelin basic protein (MBP) in the sciatic nerve.

RESULTS

SNCI resulted in deterioration of locomotor function and increased thermal pain sensitivity. The level of c-Fos expression in the PVN and vlPAG was increased and the level of NGF and MBP expression in the sciatic nerve was enhanced by SNCI. Dexmedetomidine treatment improved locomotor function and upregulated expression of NGF and MBP in the sciatic nerve of SNCI. Dexmedetomidine treatment alleviated thermal hyperalgesia and downregulated expression of c-Fos in the vlPAG and PVN after SNCI.

CONCLUSION

Dexmedetomidine may be used as a potential new treatment drug for recovery of locomotion and control of pain in peripheral nerve injury.

Peripheral Synthesis of an Atypical Protein Kinase C Mediates the Enhancement of Excitability and the Development of Mechanical Hyperalgesia Produced by Nerve Growth Factor

Nerve growth factor (NGF) plays a key role in the initiation as well as the prolonged heightened pain sensitivity of the inflammatory response. Previously, we showed that NGF rapidly augmented both the excitability of isolated rat sensory neurons and the mechanical sensitivity of the rat's hind paw. The increase in excitability and sensitivity was blocked by the myristoylated pseudosubstrate inhibitor of atypical PKCs (mPSI), suggesting that an atypical PKC may play a key regulatory role in generating this heightened sensitivity. Our findings raised the question as to whether NGF directs changes in translational control, as suggested for long-lasting long-term potentiation (LTP), or whether NGF leads to the activation of an atypical PKC by other mechanisms. The current studies demonstrate that enhanced action potential (AP) firing produced by NGF was blocked by inhibitors of translation, but not transcription. In parallel, in vitro studies showed that NGF elevated the protein levels of PKMζ, which was also prevented by inhibitors of translation. Intraplantar injection of NGF in the rat hind paw produced a rapid and maintained increase in mechanical sensitivity whose onset was delayed by translation inhibitors. Established NGF-induced hypersensitivity could be transiently reversed by injection of rapamycin or mPSI. These results suggest that NGF produces a rapid increase in the synthesis of PKMζ protein in the paw that augments neuronal sensitivity and that the ongoing translational expression of PKMζ plays a critical role in generating as well as maintaining the heightened sensitivity produced by NGF.

Nerve growth factor concentrations in the synovial fluid from healthy dogs and dogs with secondary osteoarthritis

Objective: To measure the concentrations of nerve growth factor (NGF) in the synovial fluid from normal dogs and dogs with osteoarthritis (OA) secondary to common joint disorders.

Methods: Nerve growth factor synovial concentrations were measured by ELISA assay in 50 dogs divided into three groups: 12 healthy, 16 affected by acute lameness within seven days before enrolment, and 22 with chronic lameness persisting by more than one month before enrolment and accompanied by radiological signs of OA. Both acute and chronic lameness were secondary to orthopaedic diseases involving the shoulder, elbow and stifle joints. Nerve growth factor synovial concentrations were compared between means for healthy and acute groups and between the three groups using an F-test. Significance level was set at p ±0.05.

Results: Nerve growth factor was detected in all canine synovial fluid samples. However, the mean synovial NGF concentration of healthy dogs (3.65 ± 2.18 pg/ml) was not significantly different from the mean value in dogs with acute lameness (6.45 ± 2.45 pg/ml) (p ± 0.79). Conversely, the mean synovial NGF concentration in dogs with chronic lameness (20.19 ± 17.51 pg/ml) was found to be significantly higher than that found in healthy dogs (p ±0.01).

Clinical significance: This study demonstrates for the first time the presence of NGF in canine synovial fluid and its increased concentrations in dogs with chronic lameness compared to healthy dogs and dogs with acute lameness. The association between chronic lameness and raised synovial concentrations may suggest an involvement of NGF in OA inflammation and chronic pain.

Nerve Growth Factor Expression and Its Receptors TrkA and p75NTR in Peri-Implantitis Lesions

BACKGROUND

Nerve growth factor (NGF) can, through its receptors TrkA and p75NTR, convey signals for cell survival or cell differentiation. These proteins are also involved in inflammation and in bone resorption. The aim of this study is to evaluate, for the first time, the expression of NGF and its receptors TrkA and p75NTR in peri-implantitis lesions.

MATERIALS AND METHODS

Fifteen biopsy specimens from patients with chronic peri-implantitis and 4 of healthy oral mucosa were immunostained with antibodies against NGF, TrkA, and p75NTR. The staining intensity and percentage of stained cells were semi-quantitatively evaluated and results were compared between the 2 groups.

RESULTS

In the peri-implant pocket epithelium and gingival epithelium, NGF and TrkA expressions were similar to the healthy oral mucosa, however, a decreased expression of p75NTR was observed. In all cases, more than 75% of the inflammatory cells stained positively for NGF and TrkA, and p75NTR was negatively expressed.

CONCLUSION

The intense expression of NGF and TrkA in the inflammatory cell infiltrate associated with decreased expression of p75NTR in both gingival and pocket epithelium suggests that these proteins may have a role in peri-implantitis lesions.

Customized Surgical Strategy in Chronic Pancreatitis

Despite major advances in the management of patients with chronic pancreatitis, yet the disease remains an enigmatic process of uncertain pathogenesis, unpredictable clinical course, and unclear treatment. In most of the cases intractable pain is the main indication for surgical intervention. Furthermore complications related to adjacent organs, endoscopically not permanently controlled pancreatic pseudocysts, ductal pathology, conservatively intractable internal pancreatic fistula or suspected malignancy also require surgery. The ideal surgical approach should address all these problems — tailoring the various therapeutic options to meet the individual patient's needs. In our opinion, the ideal procedure for chronic pancreatitis is the duodenum preserving pancreatic head resection in terms of an extended drainage procedure, were the extent of the pancreatic head resection may be tailored to the morphology of the pancreatic gland, thus allowing a tailored concept (to resect and/or drain as much as necessary but as little as possible). Looking at the present data, there is no need to transsect the pancreatic axis above the portal vein. If portal vein thrombosis is present, an extended drainage procedure is mandatory without transsection of the neck of the pancreas.

Detection of QTL controlling feed efficiency and excretion in chickens fed a wheat-based diet

Background

Improving feed efficiency is a major goal in poultry production in order to reduce production costs, increase the possibility of using alternative feedstuffs and decrease the volume of manure. However, in spite of their economic and environmental impact, very few quantitative trait loci (QTL) have been reported on these traits. Thus, we undertook the detection of QTL on 820 meat-type chickens from a F2 cross between D− and D+ lines that were divergently selected on low or high digestive efficiency at 3 weeks of age. Birds were measured for growth between 0 and 23 days, feed intake and feed conversion ratio between 9 and 23 days, breast and abdominal fat yields at 23 days, and the anatomy of their digestive tract (density, relative weight and length of the duodenum, jejunum, ileum, and ratio of proventriculus to gizzard weight) was examined. To evaluate excretion traits, fresh and dry weight, water content, pH, nitrogen to phosphorus ratio from 0 to 23 days, and pH of gizzard and jejunum contents at 23 days were measured. A set of 3379 single nucleotide polymorphisms distributed on 28 Gallus gallus (GGA) autosomes, the Z chromosome and one unassigned linkage group was used for QTL detection.

Results

Using the QTLMap software developed for linkage analyses by interval mapping, we detected 16 QTL for feed intake, 13 for feed efficiency, 49 for anatomy-related traits, seven for growth, six for body composition and ten for excretion. Nine of these QTL were genome-wide significant (four for feed intake on GGA1, one for feed efficiency on GGA2, and four for anatomy on GGA1, 2, 3 and 4). GGA16, 19, and 26 carried many QTL for different types of traits that co-localize at the same position.

Conclusions

This study identified several QTL regions that are involved in the control of digestive efficiency in chicken. Further studies are needed to identify the genes that underlie these effects, and to validate these in other commercial populations and for different breeding environments.

Electronic supplementary material

The online version of this article (doi:10.1186/s12711-015-0156-y) contains supplementary material, which is available to authorized users.

Nerve growth factor interactions with mast cells

Neuropeptides are involved in neurogenic inflammation where there is vasodilation and plasma protein extravasion in response to this stimulus. Nerve growth factor (NGF), identified by Rita Levi Montalcini, is a neurotrophin family compound which is important for survival of nociceptive neurons during their development. Therefore, NGF is an important neuropeptide which mediates the development and functions of the central and peripheral nervous system. It also exerts its proinflammatory action, not only on mast cells but also in B and T cells, neutrophils and eosinophils. Human mast cells can be activated by neuropeptides to release potent mediators of inflammation, and they are found throughout the body, especially near blood vessels, epithelial tissue and nerves. Mast cells generate and release NGF after degranulation and they are involved in iperalgesia, neuroimmune interactions and tissue inflammation. NGF is also a potent degranulation factor for mast cells in vitro and in vivo, promoting differentiation and maturation of these cells and their precursor, acting as a co-factor with interleukin-3. In conclusion, these studies are focused on cross-talk between neuropeptide NGF and inflammatory mast cells.

Fasinumab (REGN475), an antibody against nerve growth factor for the treatment of pain: results from a double-blind, placebo-controlled exploratory study in osteoarthritis of the knee

The safety, tolerability, and efficacy of fasinumab (REGN475), a fully human monoclonal antibody against nerve growth factor, was evaluated for the treatment of pain in patients with osteoarthritis (OA) of the knee. This was a 24-week, double-blind, placebo-controlled, parallel-group, repeat-dose, exploratory study. Eligible patients 40 to 75 years of age with a diagnosis of OA of the knee and moderate to severe pain were randomized 1:1:1:1 to intravenous fasinumab 0.03, 0.1, or 0.3 mg/kg or placebo and received study drug on day 1 and day 57. Pain intensity was recorded daily using the numeric rating scale. Safety and tolerability, assessed by the incidence of treatment-emergent adverse events (TEAEs), was the primary study endpoint. Secondary study endpoints included the change from baseline in daily walking knee pain and the assessment of pain, function, and stiffness using the Western Ontario and McMaster Osteoarthritis (WOMAC) index. Baseline characteristics were similar among treatment groups (N=217). After 24 weeks, the incidence of TEAEs ranged from 66.1% to 75.0% in the fasinumab groups vs. 63.6% for placebo. The most common TEAEs included arthralgia, hyperesthesia, myalgia, peripheral edema, and joint swelling. Discontinuation for TEAEs occurred in 5.6% of fasinumab patients and 3.7% of placebo patients. All 3 doses of fasinumab were associated with significant (P<.05) improvements compared with placebo in walking knee pain and WOMAC total and subscale scores. Fasinumab was generally well tolerated, and was associated with a significant reduction in walking knee pain and an improvement in function for up to 8 weeks.

Preliminary assessment of safety and efficacy in proof-of-concept, randomized clinical trial of tanezumab for chronic prostatitis/chronic pelvic pain syndrome

OBJECTIVE

To assess the efficacy and safety of tanezumab, a humanized monoclonal antibody directed against the pain-mediating neurotrophin, nerve growth factor, to treat pain and other symptoms of chronic prostatitis/chronic pelvic pain syndrome in a Phase IIa, proof-of-concept clinical trial powered to provide 2-sided 90% confidence interval around the primary endpoint.

METHODS

Patients received a single intravenous dose of tanezumab (20 mg) or placebo. The primary efficacy endpoint was the change from baseline to week 6 in average daily numerical rating scale pain score. The secondary endpoints included the change from baseline to week 6 in the National Institutes of Health Chronic Prostatitis Symptom Index and urinary symptoms. Safety was also assessed.

RESULTS

Overall, 62 patients were randomized (30 to tanezumab and 32 to placebo). At week 6, tanezumab marginally improved the average daily pain (least-squares mean difference from placebo -0.47, 90% confidence interval -1.150-0.209) and urgency episode frequency (least-squares mean difference from placebo -1.37, 90% confidence interval -3.146-0.401). No difference was seen in the National Institutes of Health chronic prostatitis symptom index total score or micturition frequency at week 6. The most common adverse events were paresthesia and arthralgia. The odds of having a ≥ 30% reduction in pain were 1.75-fold greater (90% confidence interval 0.65-4.69) for patients receiving tanezumab versus placebo.

CONCLUSION

Tanezumab might improve symptoms for some patients with chronic prostatitis/chronic pelvic pain syndrome. Although proof of concept was not demonstrated in the present study, additional studies with larger populations and stricter inclusion criteria according to patient phenotype might identify populations in which antinerve growth factor treatment will provide clinical benefit.

A simple technique for augmentation of axonal ingrowth into chondroitinase-treated acellular nerve grafts using nerve growth factor

BACKGROUND AND PURPOSE

Improvement in axonal regeneration may lead to the development of longer nerve grafts and improved outcomes for patients with peripheral nerve injury. Although the use of acellular nerve grafts has been well documented (Groves et al, Exp Neurol. 2005;195:278-292; Krekoski et al, J Neurosci. 2001;21:6206-6213; Massey et al, Exp Neurol. 2008;209:426-445; Neubauer et al, Exp Neurol. 2007;207:163-170; Zuo et al, Exp Neurol. 2002;176:221-228), less is known about the ability of neurotrophic factors to enhance axonal regeneration. This study evaluates axonal ingrowth augmentation using acellular, chondroitinase-treated nerve grafts doped with nerve growth factor (NGF).

METHODS

Acellular chondroitinase-treated murine nerve grafts were placed in experimental (NGF-treated grafts) and control (carrier-only grafts) rats. Five days after implantation, axonal regeneration was assessed by immunocytochemistry along with digital image analysis.

RESULTS

Higher axon count was observed throughout the length of the nerve in the NGF group (P < 0.0001), peaking at 3 mm from proximal repair (P = 0.02). Although the NGF group displayed a higher axon count per slice, the mean diameter of individual NGF axons was smaller (P < 0.0001), potentially consistent with induction of sensory axons (Rich et al, J Neurocytol. 1987;16:261-268; Sofroniew et al, Annu Rev Neurosci. 2001;24:1217-1128; Yip et al, J Neurosci. 1984;4:2986-2992).

CONCLUSION

The simple technique of doping acellular, chondroitinase-treated nerve grafts with NGF can augment axonal ingrowth and possibly preferentially induce sensory axons.

Autocrine regulation of biliary pathology by activated cholangiocytes

The bile duct system of the liver is lined by epithelial cells (i.e., cholangiocytes) that respond to a large number of neuroendocrine factors through alterations in their proliferative activities and the subsequent modification of the microenvironment. As such, activation of biliary proliferation compensates for the loss of cholangiocytes due to apoptosis and slows the progression of toxic injury and cholestasis. Over the course of the last three decades, much progress has been made in identifying the factors that trigger the biliary epithelium to remodel and grow. Because a large number of autocrine factors have recently been identified as relevant clinical targets, a compiled review of their contributions and function in cholestatic liver diseases would be beneficial. In this context, it is important to define the specific processes triggered by autocrine factors that promote cholangiocytes to proliferate, activate neighboring cells, and ultimately lead to extracellular matrix deposition. In this review, we discuss the role of each of the known autocrine factors with particular emphasis on proliferation and fibrogenesis. Because many of these molecules interact with one another throughout the progression of liver fibrosis, a model speculating their involvement in the progression of cholestatic liver disease is also presented.

[³H]serotonin release assay using antigen-stimulated rat peritoneal mast cells

The concentration of nerve growth factor (NGF) is elevated in a number of inflammatory and autoimmune states in conjunction with increased accumulation of mast cells. Mast cells, which are of hematopoietic lineage, and NGF appear to be involved in neuroimmune interactions and tissue inflammation. Mast cells themselves are capable of producing and responding to NGF. Here we describe a protocol for the isolation and culture of peritoneal-derived rat mast cells, together with a [(3)H]serotonin release assay which is useful in assessing the effects of antigens and neurotrophic factors on mast-cell activation.

Nerve growth factor derived from bronchial epithelium after chronic mite antigen exposure contributes to airway hyperresponsiveness by inducing hyperinnervation, and is inhibited by in vivo siRNA

BACKGROUND

Bronchial asthma is a chronic allergic airway inflammatory disease. Neurotrophins, including nerve growth factor (NGF), play an important role in the pathogenesis of asthma. However, the effects of NGF derived from epithelium on airway hyperresponsiveness (AHR) after antigen sensitization/exposure remain uncertain.

OBJECTIVE

In this study, we examined the role of NGF on AHR after chronic antigen exposure and the effect of inhibiting NGF by in vivo siRNA on AHR exacerbation.

METHODS

We generated chronic mouse models of bronchial asthma using house-dust mite antigen (Dermatophagoides pteronyssinus; Dp). NGF concentrations in bronchoalveolar lavage fluid (BALF), lung histopathology, hyperresponsiveness, and related neuronal peptides and cytokines in supernatants of lung homogenates were determined.

RESULTS

NGF in BALF was increased in a dose- and time-dependent manner, and was expressed primarily in bronchial epithelium. Nerve fibres and substance P-positive fibres were detected in subepithelium of Dp-sensitized and challenged mice over 4 weeks of mite antigen exposure. AHR was positively correlated with NGF concentration and nerve fibre innervation. AHR, modulation of innervation, and increased substance P were inhibited by in vivo administration of siRNA that targeted NGF, although the inhibition of NGF did not affect allergic inflammation and subepithelial fibrosis.

CONCLUSION AND CLINICAL RELEVANCE

These findings suggest that NGF derived from bronchial and alveolar epithelium plays an important role in AHR after chronic exposure to mite antigen. NGF inhibition could potentially manage bronchial asthma, including AHR.

Transsynaptic activity-dependent regulation of axon branching and neurotrophin expression in vivo

The two major classes of activity-dependent neuroplasticity predict different consequences of activity alteration on circuit response. Hebbian plasticity (positive feedback) posits that alteration of neuronal activity causes a parallel response within a circuit. In contrast, homeostatic plasticity (negative feedback) predicts that altering neuronal activity results in compensatory responses within a circuit. The relative roles of these modes of plasticity in vivo are unclear, since neuronal circuits are difficult to manipulate in the intact organism. In this study, we tested the in vivo effects of activity deprivation in the superior cervical ganglion-pineal circuit of adult rats, which can be noninvasively silenced by exposing animals to constant light. We demonstrated that total deprivation of sympathetic activity markedly decreased the presence of axonal proteins in the pineal and reduced the density and thickness of sympathetic axonal arbors. In addition, we demonstrated that sympathetic inactivity eliminated pineal function and markedly decreased pineal expression of neurotrophins. Administration of β-adrenergic agonist restored the expression of presynaptic and postsynaptic proteins. Furthermore, compensatory axonal growth through collateral sprouting, normally seen following unilateral denervation of the pineal, was profoundly impaired in the absence of neural activity. Thus, these data suggest that sympathetic axonal terminals are maintained by neural activity that induces neurotrophins, which may act through a retrograde mechanism to preserve the integrity of axonal arbors via a positive feedback loop. Conversely, by using Hebbian-like neuroplasticity, silent yet intact circuits enter a hibernation mode marked by reduction of presynaptic axonal structures and dramatically reduced postsynaptic expression of neurotrophins.

Anti-NGF treatment reduces bone resorption in periodontitis

Periodontitis is characterized by periodontal tissue destruction, including the alveolar bone. One of its critical components is the release of pro-inflammatory neuropeptides from sensory nerve endings innervating the periodontium. Since nerve growth factor (NGF) has been reported to up-regulate neuropeptides in sensory neurons, we hypothesized that it would be increased in ligature-induced periodontitis in rats, and that systemic NGF neutralization would reduce the periodontitis-associated alveolar bone resorption. Real-time PCR analysis disclosed a statistically significant time-dependent up-regulation of NGF mRNA in gingiva during 2 weeks of periodontitis. Interestingly, NGF up-regulation was also detected in the contralateral gingiva. In addition, immunohistochemistry of trigeminal ganglion neurons innervating the gingivomucosa demonstrated increased expression of TrkA receptor for NGF. Systemic anti-NGF treatment during periodontitis significantly reduced interleukin-1beta expression in gingiva and bilateral alveolar bone resorption. This suggests that NGF promotes periodontal inflammation and implicates a possible use of anti-NGF treatment in periodontitis.

Nerve growth factor as a signaling molecule for nerve cells and also for the neuroendocrine-immune systems

Nerve growth factor (NGF) is a signaling molecule, originally discovered for its role on differentiation and survival of peripheral sensory and sympathetic neurons. It has also been associated with functional activities of cells of the immune and endocrine systems. NGF biological activity is mediated by two classes of receptors: (i) p75 neurotrophin receptor (p75(NTR)), a 75 kDa glycoprotein, belonging to a superfamily of cytokine receptors including TNF receptors, and (ii) TrkA, a transmembrane tyrosine kinase of 140 kDa. Both TrkA and p75(NTR) are known to play a marked action in neurodegenerative disorders, immune-related deficits, and neuroendocrine (including adipoendocrine) mechanisms. This review focuses on these cellular events and presents a working model which attempts to explain the close interrelationships of the neuro-endocrine-immune triad via a modulatory action of NGF.

Eosinophil-nerve interactions and neuronal plasticity in rat gut associated lymphoid tissue (GALT) in response to enteric parasitism

Intestinal lymphoid tissues and Peyer's patches (PP) are innervated sites of immune surveillance in the gastrointestinal tract. Following infection with F. hepatica, neuronal hyperplasia and significantly increased eosinophil and mast cell trafficking to colonic PP sites were evident in rat tissues. Nerve-eosinophil associations were significantly elevated in infected colon and colonic PP, as were colonic tissue levels of the circulatory recruitment factors IL-5 and eotaxin. Increased immunoreactivity for neuronal plasticity markers GAP-43 and neural cell adhesion molecule (NCAM) was also found in infected tissues. Such neuronal alterations in the PP during enteric parasitism may have functional consequences on particular or pathogen uptake.

Mechanisms in prostatitis/chronic pelvic pain syndrome

PURPOSE

We reviewed the current literature on mechanisms involved in the pathogenesis of prostatitis/chronic pelvic pain syndrome (CPPS).

MATERIALS AND METHODS

A literature review for the years 1966 to 2003 was performed using the MEDLINE database of the United States National Library of Medicine.

RESULTS

National Institutes of Health categories I and II prostatitis result from identifiable prostatic infections, whereas patients with category IV are asymptomatic. The majority of symptomatic cases are category III or chronic prostatitis (CP)/CPPS. The etiology of CP/CPPS is unknown. The traditional marker of inflammation, namely white blood cells in prostatic fluids, does not correlate with the predominant symptom of pelvic pain. An imbalance toward increased proinflammatory and decreased anti-inflammatory cytokines has been implicated and a few studies have shown some correlation of this with pelvic pain. The imbalance in some men may result from polymorphisms at the cytokine loci. An autoimmune process may be involved and experimental evidence indicates that this can be under hormonal influence. Recent findings include possible defects in the androgen receptor. The prostate may not even be the source of the symptoms. Pelvic pain also correlates with the neurotrophin nerve growth factor implicated in neurogenic inflammation and central sensitization. Finally, psychological stress may produce measurable biochemical changes and influence the other processes. The role of normal prostatic bacterial flora in inciting the inflammatory response has also been reconsidered.

CONCLUSIONS

The symptoms of CP/CPPS appear to result from an interplay between psychological factors and dysfunction in the immune, neurological and endocrine systems.

Herpes simplex virus-thymidine kinase-based suicide gene therapy as a "molecular switch off" for nerve growth factor production in vitro

Tissue-engineered constructs offer a new hope to patients suffering from functional impairment after nerve injury. An effort has been made to focus on delivery, regulation, and "molecular shutoff" of nerve growth factor (NGF) in tissue-engineered constructs. We have previously demonstrated that human embryonic kidney (HEK-293) cells can be genetically modified to secrete NGF at varying time points upon up regulation with Ponasterone A (PonA) both in vitro and in vivo. In the present study, HEK-293 cells that stably and inducibly produce NGF were further stably transfected with herpes simplex virus-thymidine kinase gene as a suicide gene (hNGF-EcR-293-TK) in order to shut off the NGF secretion and kill the cells upon treatment with ganciclovir (GCV). These cells following induction with PonA secreted NGF levels of 6659.2 +/- 489.4 pg/mL at day 10 postbooster dose at day 5, which was significantly higher than the control noninduced cells. The NGF secreted by these cells was bioactive as determined by a rat adrenal pheochromocytoma (PC-12) cell bioassay. Treatment of these cells with GCV significantly reduced the NGF levels to 645.3 +/- 16.2 pg/mL at day 10 and live cell numbers dropped to 7.95 x 10(3) +/- 278 compared to 2.73 x 10(5) +/- 6.1 x 10(4). GCV-treated cell media when transferred to the PC-12 cell bioassay demonstrated less than 10% cells differentiating into neurite-like extensions. We conclude that hNGF-EcR-293-TK cells can inducibly secrete bioactive NGF when treated with the inducing agent and can also be killed upon treatment with GCV. This double-gene transfection for gene expression and molecular shutoff mechanism will be a useful tool in tissue-engineered nerve constructs.

The function neutralizing anti-TrkA antibody MNAC13 reduces inflammatory and neuropathic pain

Nerve growth factor (NGF) is involved in pain transduction mechanisms and plays a key role in many persistent pain states, notably those associated with inflammation. On this basis, both the NGF ligand and its receptor TrkA (tyrosine kinase A) represent an eligible target for pain therapy. Although the direct involvement of NGF in pain modulation is well established, the effect of a direct functional block of the TrkA receptor is still unknown. In this study, we have demonstrated that MNAC13, the only anti-TrkA monoclonal antibody for which function neutralizing properties have been clearly shown both in vitro and in vivo, induces analgesia in both inflammatory and neuropathic pain models, with a surprisingly long-lasting effect in the latter. The formalin-evoked pain licking responses are significantly reduced by the MNAC13 antibody in CD1 mice. Remarkably, treatment with the anti-TrkA antibody also produces a significant antiallodynic effect on neuropathic pain: repeated i.p. injections of MNAC13 induce significant functional recovery in mice subjected to sciatic nerve ligation, with effects persisting after administration. Furthermore, a clear synergistic effect is observed when MNAC13 is administered in combination with opioids, at doses that are not efficacious per se. This study represents a direct demonstration that neutralizing antibodies directed against the TrkA receptor may display potent analgesic effects in inflammatory and chronic pain.

Molecular evolution of the neurotrophin family members and their Trk receptors

Neurotrophins are structurally related proteins regulating brain development and function. Molecular evolution studies of neurotrophins and their receptors are essential for understanding the mechanisms underlying the coevolution processes of these gene families and how they correlate with the increased complexity of the vertebrate nervous system. In order to improve our current knowledge of the molecular evolution of neurotrophins and receptors, we have collected all information available in the literature and analyzed the genome database for each of them. Statistical analysis of aminoacid and nucleotide sequences of the neurotrophin and Trk family genes was applied to both complete genes and mature sequences, and different phylogenetic methods were used to compare aminoacid and nucleotide sequences variability among the different species. All collected data favor a model in which several rounds of genome duplications might have facilitated the generation of the many different neurotrophins and the acquisition of specific different functions correlated with the increased complexity of the vertebrate nervous system during evolution. We report findings that refine the structure of the evolutionary trees for neurotrophins and Trk receptors families, indicate different rates of evolution for each member of the two families, and newly demonstrate that the NGF-like genes found in Fowlpox and Canarypox viruses are closely related to reptile NGF.

Effect of chronic olanzapine treatment on nerve growth factor and brain-derived neurotrophic factor in the rat brain

Nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) are proteins involved in neuronal survival, neurite outgrowth and synapse formation. Recent observations suggest that treatment with typical and atypical antipsychotic drugs affect NGF and BDNF levels in the rat brain. The atypical antipsychotic olanzapine has a low incidence of side effects, such as extrapyramidal and anticholinergic symptoms. Since NGF and BDNF are involved in the regulation of cholinergic, dopaminergic and serotonergic neurons in the central nervous system (CNS) we hypothesized that chronic olanzapine treatment will influence the distribution of NGF and BDNF in the rat brain. To test this hypothesis we administered olanzapine for 29 days in the drinking water at the doses of 3 and 15 mg/kg body weight and measured the levels of NGF and BDNF in the brain of Wistar rats. Olanzapine increased NGF in the hippocampus, occipital cortex and hypothalamus. In contrast, olanzapine decreased BDNF in the hippocampus and frontal cortex. Although the significance of these findings is not clear, a heuristic hypothesis is that olanzapine's clinical effects and a favorable side effect profile are in part mediated by neurotrophins.

Nerve Growth Factor Expression Response to Induction Agent Booster Dosing in Transfected Human Embryonic Kidney Cells

To assess whether nerve growth factor (NGF) expression would respond to booster dosing with the inducing agent ponasterone A, human embryonic kidney cells (HEK-293) were transfected with human NGF cDNA. Cells were cultured for 5 days in media with or without ponasterone A. On day 5, controls received a ponasterone A media replacement, whereas experimental groups received ponasterone A booster media replacement. NGF protein expression bioactivity was assessed using a PC-12 cell bioassay and the concentration of secreted NGF was quantified using NGF enzyme-linked immunosorbent assay. Cells with and without ponasterone A were left for 5 days without changing the medium. On day 5, the supernatants were collected and flash-frozen for enzyme-linked immunosorbent assay. The ponasterone A-positive and -negative booster medium was replaced in the appropriate wells. Supernatants were collected from the wells at 2, 4, and 6 days after the booster dose and removal of original supernatant. The medium was flash-frozen for enzyme-linked immunosorbent assay (1.5 ml), and the remaining 500 mul was transferred to PC-12 cells seeded onto 12-well plates to determine NGF bioactivity. All experiments were performed in quadruplicate. NGF production was measured daily by enzyme-linked immunosorbent assay over a 6-day period after the ponasterone A booster to a maximal release of 1233 +/- 130 pg/ml at day 6 (11 days after original induction). Maximal NGF production per 10(3) cells was 2.5 +/- 0.61 pg at day 6. Bioactivity was determined by percentage differentiation (per 100 cells counted) at 26, 52, and 98 percent for ponasterone A-treated wells on 2, 4, and 6 days after booster dosing (7, 9, and 11 days after induction), respectively. PC-12 cell differentiation was not visualized in the ponasterone A-negative control wells. Human NGF-EcR-293 cells can inducibly secrete bioactive NGF when exposed to the induction agent ponasterone A. Furthermore, repeated bioactive NGF expression peaks beyond that previously demonstrated can be achieved using induction agent booster dosing, indicating the ability to regulate the system over an extended period.

Study of visceral hypersensitivity in irritable bowel syndrome

OBJECTIVE

Visceral hypersensitivity is highly prevalent in most functional bowel disorders, such as irritable bowel syndrome (IBS), and activation of intestinal mast cells (MC) may play a role because they have been found in close proximity to gastrointestinal mucosal sensory nerve terminals containing neuropeptides and a bi-directional pathway connecting the central nervous system, gut, and MC has been demonstrated. The current study appraised the status of rectal visceral perception, as well as the changes in the MC and substance P (SP) in the intestinal mucosa of patients with IBS.

METHODS

The study group comprised 42 patients with IBS and 19 healthy subjects who underwent anorectal manometry and rectal perception thresholds to balloon distension. The MC and the SP-ergic terminals in the mucosa were stained for respective histochemical and immunohistochemical investigations. The results were presented both qualitatively and quantitatively by color image analyzer, based on analysis of the intensity and area of stained fibrils. The structural relationship between the MC and nerve terminals was studied by electron microscopy, using an in situ embedding technique.

RESULTS

The anorectal resting pressure, squeezing pressure and relaxation pressure were normal in both groups. The sensation threshold, defecation threshold and pain threshold in diarrhea-predominant IBS and the pain thresholds in constipation-predominant IBS were much lower than in the controls. Rectal compliance decreased in IBS. The number of MC in the terminal ileum, the ileocecal junction and the ascending colon was significantly elevated in IBS (P < 0.01), and the MC showed great variation. A significantly increased concentration of SP was found in the colon of the IBS patients compared with the controls. There was a positive correlation between the profiles of mucosal MC and the SP-ergic terminals, and MC were closely adjacent to SP-ergic terminals in the lamina propria.

CONCLUSION

As altered rectal perception is present in almost all patients with IBS, it might be a reliable biological characteristic of the disease. Alterations in the MC and SP of the intestinal mucosa may be important factors in visceral hypersensitivity.

Nerve growth factor modulates the proliferative capacity of the intrahepatic biliary epithelium in experimental cholestasis

BACKGROUND & AIMS

We evaluated the expression of neurotrophins in rat cholangiocytes and the role and mechanisms by which nerve growth factor (NGF) modulates cholangiocyte proliferation.

METHODS

The expression of neurotrophins and their receptors was investigated by immunohistochemistry in liver sections and reverse-transcription polymerase chain reaction and immunoblots in isolated cholangiocytes. In vitro, the effect of NGF on cholangiocyte proliferation and signal transduction was investigated by immunoblotting for proliferating cell nuclear antigen, phosphorylated AKT (p-AKT), phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2), phosphorylated c-jun-N-terminal kinase, and phosphorylated p38. In vivo, rats that had undergone bile duct ligation (BDL) were treated with an anti-NGF antibody to immunoneutralize NGF and bile duct mass, proliferation, apoptosis, and inflammation were investigated by immunohistochemistry.

RESULTS

NGF and its TrkA receptor were expressed by normal rat cholangiocytes and up-regulated following BDL. Cholangiocytes secrete NGF, and secretion is increased in proliferating BDL cholangiocytes. In vitro, NGF stimulated cholangiocyte proliferation, which was associated with enhanced p-AKT and p-ERK1/2 expression. NGF proliferation in vitro was partially blocked by the MEK inhibitor (UO126) and completely ablated by the phosphatidylinositol 3-kinase inhibitor (wortmannin). In vitro, NGF and estrogens have an additive effect on cholangiocyte proliferation by acting on phosphorylated TrkA and p-ERK1/2. In vivo, immunoneutralization of NGF decreased bile duct mass in BDL rats, which was associated with depressed proliferation and enhanced apoptosis and with increased portal inflammation.

CONCLUSIONS

Cholangiocytes secrete NGF and express NGF receptors. NGF induces cholangiocyte proliferation by activating the ERK and, predominantly, the phosphatidylinositol 3-kinase pathway and exerts an additive effect in combination with estrogens on proliferation.

Mechanisms in prostatitis/chronic pelvic pain syndrome

PURPOSE

We reviewed the current literature on mechanisms involved in the pathogenesis of prostatitis/chronic pelvic pain syndrome (CPPS).

MATERIALS AND METHODS

A literature review for the years 1966 to 2003 was performed using the MEDLINE database of the United States National Library of Medicine.

RESULTS

National Institutes of Health categories I and II prostatitis result from identifiable prostatic infections, whereas patients with category IV are asymptomatic. The majority of symptomatic cases are category III or chronic prostatitis (CP)/CPPS. The etiology of CP/CPPS is unknown. The traditional marker of inflammation, namely white blood cells in prostatic fluids, does not correlate with the predominant symptom of pelvic pain. An imbalance toward increased proinflammatory and decreased anti-inflammatory cytokines has been implicated and a few studies have shown some correlation of this with pelvic pain. The imbalance in some men may result from polymorphisms at the cytokine loci. An autoimmune process may be involved and experimental evidence indicates that this can be under hormonal influence. Recent findings include possible defects in the androgen receptor. The prostate may not even be the source of the symptoms. Pelvic pain also correlates with the neurotrophin nerve growth factor implicated in neurogenic inflammation and central sensitization. Finally, psychological stress may produce measurable biochemical changes and influence the other processes. The role of normal prostatic bacterial flora in inciting the inflammatory response has also been reconsidered.

CONCLUSIONS

The symptoms of CP/CPPS appear to result from an interplay between psychological factors and dysfunction in the immune, neurological and endocrine systems.

Capsular neuronal elements and their relation to pain reduction and functional improvement following total hip replacement

We studied changes of pain intensity and functional impairment in 22 patients with osteoarthrosis undergoing total hip replacement. Using a visual analogue scale, the mean scores for pain and disability before surgery were 71.7 and 70.9 respectively. Both scores showed gradual improvement during a 1-year follow-up period, with more than 90% of the total improvement occurring within the first 3 months. After 1 year, the scores for pain and disability were 11.9 and 4.1 respectively. The hip joint capsule was studied using immunohistochemistry to detect neurofilaments. Neurofilament immunoreactivity was observed in 16/22 cases and was correlated with pain and disability scores. However, there were no correlations between pre- and postoperative pain scores, the score changes, and the quantity of capsular neurofilaments. Thus, other factors than capsular neurofilaments influence the scores of pain and disability in osteoarthritis.

Increased serum concentration of nerve growth factor in patients with microprolactinoma

Nerve growth factor (NGF) is known to play a role as a circulating neurokine, integrating signals from the neuro-immuno-endocrine system. The ability of NGF to activate the pituitary-adrenocortical axis, together with the increase of its serum concentration in pregnancy and lactation, supports the hypothesis that NGF is secreted by the pituitary gland and plays a role as modulator of endocrine functions. Evidence obtained both in vitro and in vivo in experimental animal models suggests that lactotroph cells secrete both prolactin (PRL) and NGF. Furthermore, in previous studies we demonstrate that cell lines derived from dopamine (DA)-sensitive human prolactinomas express high levels of NGF messenger RNA and protein. On these basis, we studied serum NGF concentrations in female patients with microprolactinoma (n = 4) and in control women (n = 5). PRL and NGF were measured at the diagnosis, during the thyrotropin releasing hormone (TRH) test and after the therapy with DA D2 receptor agonist cabergoline (0.25 mg, twice a week). Results obtained suggested that hyperprolactinemia (70.3+/-8.4 ng/ml) paralleled markedly higher NGF levels (58.4+/-18.7 pg/ml) compared to controls (PRL 8.7+/-3.2 ng/ml, NGF 8.4+/-1.3 pg/ml). Serum concentrations of NGF and PRL during the TRH test were closely associated (r = 0.943, p < 0.01). Cabergoline therapy normalized PRL (7.9+/-3.6 ng/ml) and induced a significant decrease of NGF levels (12.5+/-4.9 pg/ml). In conclusions, data reported here indicated that, in human microprolactinomas, NGF is released in the bloodstream paralleling PRL-secretion and it is modulated by a neurotransmitter-regulated mechanism, since the normalization of PRL elicited by the DA D2 receptor agonist cabergoline induced a significant decrease of serum NGF as well.

Human Embryonic Kidney Cells (HEK-293 Cells): Characterization and Dose-Response Relationship for Modulated Release of Nerve Growth Factor for Nerve Regeneration

The development of engineered constructs to bridge nerve gaps may hold the key to improved functional outcomes in the repair of injured peripheral nerves. These constructs must be rendered bioactive by providing the growth factors required for successful peripheral nerve regeneration. Previous studies demonstrated that harvested human and rat dermal fibroblasts could be genetically engineered to release nerve growth factor (NGF) both in vitro and in vivo. The use of fibroblasts, however, has the potential to cause scarring, and the expression of NGF from those cells was transient. To overcome these potential difficulties, human embryonic kidney cells were modified for use with the ecdysone-inducible mammalian expression system. These cells (hNGF-EcR-293) have been engineered and regulated to secrete human NGF in response to the ecdysone analogue ponasterone A. HEK-293 cells were transfected with human NGF cDNA with the ecdysone-inducible mammalian expression system (Invitrogen, Carlsbad, Calif.). Stable clones were then selected. Ponasterone A, an analogue of ecdysone, was used as the inducing agent. The secretion of NGF into the medium was analyzed with two different methods. After 24 hours of exposure to the inducing agent, cell medium was transferred to PC-12 cells seeded in 12-well plates, for determination of whether the secreted NGF was bioactive. Medium from untreated or ponasterone A-treated hNGF-EcR-293 cells was deemed bioactive on the basis of its ability to induce PC-12 cell differentiation. The concentrations of secreted NGF were also quantified with an enzyme-linked immunosorbent assay, in triplicate. NGF production was measured in successive samples of the same medium during a 9-day period, with maximal release of 9.05 +/- 2.6 ng/ml at day 9. Maximal NGF production was 8.46 +/- 2.1 pg/10(3) cells at day 9. These levels were statistically significantly different from levels in noninduced samples (p <or= 0.05). Differences in NGF secretion with the three different concentrations of ponasterone A (1, 2, and 3 microM) were not statistically significant. PC-12 cells exposed to medium from induced transfected HEK-293 cells demonstrated markedly higher levels of differentiation, compared with control levels, indicating bioactive protein secretion. It was demonstrated that this regulated delivery system could secrete bioactive NGF for up to 9 days and might be useful for in vivo applications. This regulated delivery system should be useful for tissue-engineered nerve constructs.

Macrophage Migration Inhibitory Factor Is Upregulated in an Endotoxin-Induced Model of Bladder Inflammation in Rats

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine found in epithelial cells as preformed stores, such that MIF release can activate innate immune responses. Our identification of MIF stores in the urothelium suggests that MIF may function in the bladder's initial response to infectious stimuli, such as lipopolysaccharide (LPS). To test this hypothesis, we observed changes in MIF, cyclooxygenase-2 (COX-2) and c-fos in the bladder, L6-S1 spinal cord, dorsal root ganglion (DRG), and major pelvic ganglion (MPG) and MIF changes in the prostate following intravesical LPS. Intravesical LPS induced bladder edema and leukocyte infiltration, as well as increased MIF protein and mRNA in the bladder and lumbosacral spinal cord. Expression of immediate-early gene c-fos, a transcription factor used as a marker of neuronal activation, increased in the L6-S1 spinal cord and L6-S1 DRG of rats that received LPS. We conclude that significant increases in bladder MIF expression and protein in response to intravesical LPS may represent part of this organ's initial innate immune response. In addition, MIF upregulation may represent a neural response to visceral inflammation. Finally, changes in prostate MIF content after intravesical LPS suggest that MIF may be involved in viscerovisceral interactions associated with chronic pelvic pain syndromes.

Endothelial cells play an essential role in the thermal hyperalgesia induced by nerve growth factor

Nerve growth factor (NGF) is a potent mediator of inflammatory hyperalgesia, in addition to roles in the development and maintenance of neurons. We provide evidence for the novel concept that microvascular endothelial cells play a critical primary role in NGF-mediated events that lead to inflammatory hyperalgesia in rat skin. We show that, surprisingly, neutrophils are not directly activated by NGF, although local administration of NGF mediates thermal hyperalgesia via mechanisms involving concomitant neutrophil accumulation. The co-administration of actinomycin D with NGF negated both neutrophil accumulation and thermal hyperalgesia, indicating the dependence of NGF on local de novo protein synthesis. More significantly, an antibody against the endothelial-derived adhesion molecule ICAM-1 also blocked neutrophil accumulation and thermal hyperalgesia. Finally the ability of NGF to stimulate ICAM-1 in human cultured umbilical vein endothelial cells is shown. We propose that NGF acts primarily to activate endothelial cells and that this response is essential for the ensuing neutrophil accumulation and hyperalgesia. The findings reveal a central role of the endothelial cell in initiating NGF-dependent inflammatory hyperalgesia and emphasize the importance of further investigations aimed at examining the feasibility of new therapeutic strategies that target NGF.