Nerve growth factor and tissue repair remodeling: trkA(NGFR) and p75(NTR), two receptors one fate

The History of Nerve Growth Factor: From Molecule to Drug

Nerve growth factor (NGF), the first neurotrophin to be discovered, has a long and eventful research journey with a series of turning points, setbacks, and achievements. Since the groundbreaking investigations led by Nobel Prize winner Rita Levi-Montalcini, advancements in the comprehension of NGF's functions have revolutionized the field of neuroscience, offering new insights and opportunities for therapeutic innovation. However, the clinical application of NGF has historically been hindered by challenges in determining appropriate dosing, administration strategies, and complications related to the production process. Recent advances in the production and scientific knowledge of recombinant NGF have enabled its clinical development, and in 2018, the United States Food and Drug Administration approved cenegermin-bkbj, a recombinant human NGF, for the treatment of all stages of neurotrophic keratitis. This review traces the evolutionary path that transformed NGF from a biological molecule into a novel therapy with potential research applications beyond the eye. Special emphasis is put on the studies that advanced NGF from discovery to the first medicinal product approved to treat a human disease.

Near-infrared light responsive gold nanoparticles coating endows polyetheretherketone with enhanced osseointegration and antibacterial properties

Polyetheretherketone (PEEK) is considered as a promising dental implant material owing to its excellent physicochemical and mechanical properties. However, its wide range of applications is limited by its biologically inert nature. In this study, a near-infrared (NIR) light responsive bioactive coating with gold nanoparticles (AuNPs) and metronidazole adhered to the PEEK surface via dopamine polymerization. Compared to pure PEEK, the hydrophilicity of the treated PEEK surface was significantly improved. In addition, under NIR light, the surface coating exhibited photothermal conversion effect, and gold nanoparticles and the antibiotic can be released from the coating. This improved the antibacterial properties of PEEK materials. Moreover, the coating was more conducive to the early adhesion of bone mesenchymal stem cells. The results of in vitro and in vivo osteogenic activity studies showed that the developed coating promoted osseointegration of PEEK implants, and NIR light irradiation further improved the antibacterial ability and osteogenic activity of PEEK implants. Through RNA sequencing, the potential underlying mechanism of promoting bone formation of the AuNPs coating combined metronidazole was interpreted. In summary, the developed coating is a potential surface treatment strategy that endows PEEK with enhanced osseointegration and antibacterial properties.

Nerve Growth Factor-Preconditioned Mesenchymal Stem Cell-Derived Exosome-Functionalized 3D-Printed Hierarchical Porous Scaffolds with Neuro-Promotive Properties for Enhancing Innervated Bone Regeneration

The essential role of the neural network in enhancing bone regeneration has often been overlooked in biomaterial design, leading to delayed or compromised bone healing. Engineered mesenchymal stem cells (MSCs)-derived exosomes are becoming increasingly recognized as potent cell-free agents for manipulating cellular behavior and improving therapeutic effectiveness. Herein, MSCs are stimulated with nerve growth factor (NGF) to regulate exosomal cargoes to improve neuro-promotive potential and facilitate innervated bone regeneration. In vitro cell experiments showed that the NGF-stimulated MSCs-derived exosomes (N-Exos) obviously improved the cellular function and neurotrophic effects of the neural cells, and consequently, the osteogenic potential of the osteo-reparative cells. Bioinformatic analysis by miRNA sequencing and pathway enrichment revealed that the beneficial effects of N-Exos may partly be ascribed to the NGF-elicited multicomponent exosomal miRNAs and the subsequent regulation and activation of the MAPK and PI3K-Akt signaling pathways. On this basis, N-Exos were delivered on the micropores of the 3D-printed hierarchical porous scaffold to accomplish the sustained release profile and extended bioavailability. In a rat model with a distal femoral defect, the N-Exos-functionalized hierarchical porous scaffold significantly induced neurovascular structure formation and innervated bone regeneration. This study provided a feasible strategy to modulate the functional cargoes of MSCs-derived exosomes to acquire desirable neuro-promotive and osteogenic potential. Furthermore, the developed N-Exos-functionalized hierarchical porous scaffold may represent a promising neurovascular-promotive bone reparative scaffold for clinical translation.

The Impact of ROS and NGF in the Gliomagenesis and their Emerging Implications in the Glioma Treatment

Reactive oxygen species (ROS) are highly reactive molecules derived from molecular oxygen (O2). ROS sources can be endogenous, such as cellular organelles and inflammatory cells, or exogenous, such as ionizing radiation, alcohol, food, tobacco, chemotherapeutical agents and infectious agents. Oxidative stress results in damage of several cellular structures (lipids, proteins, lipoproteins, and DNA) and is implicated in various disease states such as atherosclerosis, diabetes, cancer, neurodegeneration, and aging. A large body of studies showed that ROS plays an important role in carcinogenesis. Indeed, increased production of ROS causes accumulation in DNA damage leading to tumorigenesis. Various investigations demonstrated the involvement of ROS in gliomagenesis. The most common type of primary intracranial tumor in adults is represented by glioma. Furthermore, there is growing attention on the role of the Nerve Growth Factor (NGF) in brain tumor pathogenesis. NGF is a growth factor belonging to the family of neurotrophins. It is involved in neuronal differentiation, proliferation and survival. Studies were conducted to investigate NGF pathogenesis's role as a pro- or anti-tumoral factor in brain tumors. It has been observed that NGF can induce both differentiation and proliferation in cells. The involvement of NGF in the pathogenesis of brain tumors leads to the hypothesis of a possible implication of NGF in new therapeutic strategies. Recent studies have focused on the role of neurotrophin receptors as potential targets in glioma therapy. This review provides an updated overview of the role of ROS and NGF in gliomagenesis and their emerging role in glioma treatment.

Exploration of the prognostic effect of costimulatory genes in bladder cancer

BACKGROUND

A prognostic model of bladder cancer was constructed based on costimulatory molecules, and its stability and accuracy were verified in different datasets.

METHOD

The expression profile of bladder cancer RNA and the corresponding clinical data in The Cancer Genome Atlas (TCGA) database were analyzed employing computational biology, and a prognostic model was constructed for costimulating molecule-related genes. The model was applied in GSE160693, GSE176307, Xiangya_Cohort, GSE13507, GSE19423, GSE31684, GSE32894, GSE48075, GSE69795 and GSE70691 in TCGA dataset and Gene Expression Omnibus database. The role of costimulating molecules in bladder cancer tumor subtypes was also explored. By consistent cluster analysis, bladder cancer in the TCGA dataset was categorized into two subtypes: C1 and C2. The C1 subtype exhibited a poor prognosis, high levels of immune cell infiltration and significant enrichment of natural killer cells, T cells and dendritic cells in the C1 subtype. In addition, the ImmuneScore calculated by the ESTIMATE algorithm differed greatly between the two subtypes, and the ImmuneScore of the C1 subtype was greater than the C2 subtype in a significant manner.

RESULTS

This study also assessed the relationship between costimulating molecules and immunotherapy response. The high-risk group responded poorly to immunotherapy, with significant differences in the amount of most immune cells between the two groups. Further, three indices of the ESTIMATE algorithm and 22 immune cells of the CIBERSORT algorithm were significantly correlated with risk values. These findings suggest the potential value of costimulating molecules in predicting immunotherapy response.

CONCLUSION

A costimulatory molecule-based prognostic model for bladder cancer was established and validated across multiple datasets. This model introduces a novel mode for tailoring treatments to each individual with bladder cancer, and offers valuable insights for informed clinical choices. Simultaneously, this research also delved into the significance of costimulating molecules within distinct bladder cancer subtypes, shedding novel insights into improving immunotherapy strategies for the treatment of bladder cancer.

An in silico study of protein-protein interactions and design of novel peptides for TrkA in ameloblastoma

Ameloblastoma is a benign odontogenic jawbone tumor. The binding of Nerve growth factor (NGF) to receptor tyrosine kinase A (TrkA) promotes cell survival, proliferation, and differentiation via PI3K/AKT and Ras/MAPK signaling. Although the exact cause of ameloblastoma remains unknown, elevated levels of NGF and TrkA expression in ameloblastoma are associated with aggressive tumor behavior and poor patient outcomes. It is previously demonstrated that His 4, Arg 9, and Glu 11 residues of NGF made crucial interactions with the TrkA subunit. The main aim of our present study to develop potential therapeutic strategies by identifying promising peptide candidates. The objectives include starting with a detailed in silico analysis to identify a crucial peptide sequence of NGF that is bound by TrkA, creating a library of novel peptides from the identified peptide sequence through a single-point mutation on interacting residues (His 4, Arg 9, and Glu 11), and selecting the top peptides based on docking score, interactions analysis, and desirable pose analysis. The study ultimately designed a hybrid peptide candidate through the simultaneous and continuous mutation of the top residues, resulting in a peptide that exhibited a more specific interaction with TrkA, blocking the binding site and preventing the interaction between NGF and TrkA.Communicated by Ramaswamy H. Sarma.

A Novel Perspective on Neuronal Control of Anatomical Patterning, Remodeling, and Maintenance

While the nervous system may be best known as the sensory communication center of an organism, recent research has revealed a myriad of multifaceted roles for both the CNS and PNS from early development to adult regeneration and remodeling. These systems work to orchestrate tissue pattern formation during embryonic development and continue shaping pattering through transitional periods such as metamorphosis and growth. During periods of injury or wounding, the nervous system has also been shown to influence remodeling and wound healing. The neuronal mechanisms responsible for these events are largely conserved across species, suggesting this evidence may be important in understanding and resolving many human defects and diseases. By unraveling these diverse roles, this paper highlights the necessity of broadening our perspective on the nervous system beyond its conventional functions. A comprehensive understanding of the complex interactions and contributions of the nervous system throughout development and adulthood has the potential to revolutionize therapeutic strategies and open new avenues for regenerative medicine and tissue engineering. This review highlights an important role for the nervous system during the patterning and maintenance of complex tissues and provides a potential avenue for advancing biomedical applications.

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

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

Epigenetic Regulation of NGF-Mediated Osteogenic Differentiation in Human Dental Mesenchymal Stem Cells

Nerve growth factor (NGF) is the best-characterized neurotrophin and is primarily recognized for its key role in the embryonic development of the nervous system and neuronal cell survival/differentiation. Recently, unexpected actions of NGF in bone regeneration have emerged as NGF is able to enhance the osteogenic differentiation of mesenchymal stem cells. However, little is known regarding how NGF signaling regulates osteogenic differentiation through epigenetic mechanisms. In this study, using human dental mesenchymal stem cells (DMSCs), we demonstrated that NGF mediates osteogenic differentiation through p75NTR, a low-affinity NGF receptor. P75NTR-mediated NGF signaling activates the JNK cascade and the expression of KDM4B, an activating histone demethylase, by removing repressive H3K9me3 epigenetic marks. Mechanistically, NGF-activated c-Jun binds to the KDM4B promoter region and directly upregulates KDM4B expression. Subsequently, KDM4B directly and epigenetically activates DLX5, a master osteogenic gene, by demethylating H3K9me3 marks. Furthermore, we revealed that KDM4B and c-Jun from the JNK signaling pathway work in concert to regulate NGF-mediated osteogenic differentiation through simultaneous recruitment to the promoter region of DLX5. We identified KDM4B as a key epigenetic regulator during the NGF-mediated osteogenesis both in vitro and in vivo using the calvarial defect regeneration mouse model. In conclusion, our study thoroughly elucidated the molecular and epigenetic mechanisms during NGF-mediated osteogenesis.

Nerve Growth Factor (NGF) as Partaker in the Modulation of UV-Response in Cultured Human Conjunctival Fibroblasts

Corroborating data sustain the pleiotropic effect of nerve growth factor (NGF) in the protection of the visual system from dangerous stimuli, including ultraviolet (UV). Since UV exposure might promote ocular surface changes (conjunctival inflammation and matrix rearrangement), as previously reported from in vivo studies sustaining some protective NGF effects, in vitro cultures of human conjunctival fibroblasts (FBs) were developed and exposed to a single UV exposure over 15 min (0.277 W/m²), either alone or supplemented with NGF (1–10–100 ng/mL). Conditioned media and cell monolayers were collected and analyzed for protein release (ELISA, ELLA microfluidic) and transcript expression (real-time PCR). A specific “inflammatory to remodeling” pattern (IL8, VEGF, IL33, OPN, and CYR61) as well as a few epigenetic transcripts (known as modulator of cell differentiation and matrix-remodeling (DNMT3a, HDAC1, NRF2 and KEAP1)) were investigated in parallel. UV-exposed FBs (i), showed no proliferation or significant cytoskeleton rearrangement; (ii), displayed a trkA^NGFR/p75^NTR phenotype; and (iii), synthesized/released IL8, VEGF-A, IL33, OPN, and CYR61, as compared to unexposed ones. NGF addition counteracted IL8, IL33, OPN, and CYR61 protein release merely at lower NGF concentrations but not VEGF. NGF supplementation did not affect DNMT3a or HDAC1 transcripts, while it significantly upregulated NRF2 at lowest NGF doses and did not change KEAP1 expression. Taken together, a single UV exposure activated conjunctival FBs to release pro-inflammatory/fibrogenic factors in association with epigenetic changes. The effects were selectively counteracted by NGF supplementation in a dose-dependent fashion, most probably accountable to the trkA^NGFR/p75^NTR phenotype. Further in vitro studies are underway to better understand this additional NGF pleiotropic effect. Since UV-shield impairments represent a worldwide alert and UV radiation can slowly affect ocular surface homeostasis (photo-ageing, cataract) or might exacerbate ocular diseases with a preexisting fibrosis (pterygium, VKC), these findings on NGF modulation of UV-exposed FBs might provide additional information for protecting the ocular surface (homeostasis) from low-grade long-lasting UV insults.

Correlations Between the Expression of Stromal Cell Activation Related Biomarkers, L-NGFR, Phospho-ERK1-2 and CXCL12, and Primary Myelofibrosis Progression

In myelofibrosis, pathologically enhanced extracellular matrix production due to aberrant cytokine signalling and clonal megakaryocyte functions result(s) in impaired hemopoiesis. Disease progression is still determined by detecting reticulin and collagen fibrosis with Gomori’s silver impregnation. Here, we tested whether the expression growth related biomarkers L-NGFR/CD271, phospho-ERK1-2 and CXCL12 can be linked to the functional activation of bone marrow stromal cells during primary myelofibrosis progression. Immunoscores for all tested biomarkers showed varying strength of positive statistical correlation with the silver impregnation based myelofibrosis grades. The intimate relationship between spindle shaped stromal cells positive for all three markers and aberrant megakaryocytes was likely to reflect their functional cooperation. L-NGFR reaction was restricted to bone marrow stromal cells and revealed the whole length of their processes. Also, L-NGFR positive cells showed the most intersections, the best statistical correlations with myelofibrosis grades and the strongest interrater agreements. CXCL12 reaction highlighted stromal cell bodies and a weak extracellular staining in line with its constitutive release. Phospho-ERK1-2 reaction showed a similar pattern to CXCL12 in stromal cells with an additional nuclear staining in agreement with its role as a transcription factor. Both p-ERK1-2 and CXCL12 were also expressed at a moderate level in sinus endothelial cells. Connexin 43 gap junction communication channels, known to be required for CXCL12 release to maintain stem cell niche, were also expressed progressively in the myelofibrotic stromal network as a support of compartmental functions. Our results suggest that, diverse growth related pathways are activated in the functionally coupled bone marrow stromal cells during myelofibrosis progression. L-NGFR expression can be a useful biological marker of stromal cell activation which deserves diagnostic consideration for complementing Gomori’s silver impregnation.

Understanding Drivers of Ocular Fibrosis: Current and Future Therapeutic Perspectives

Ocular fibrosis leads to severe visual impairment and blindness worldwide, being a major area of unmet need in ophthalmology and medicine. To date, the only available treatments are antimetabolite drugs that have significant potentially blinding side effects, such as tissue damage and infection. There is thus an urgent need to identify novel targets to prevent/treat scarring and postsurgical fibrosis in the eye. In this review, the latest progress in biological mechanisms underlying ocular fibrosis are discussed. We also summarize the current knowledge on preclinical studies based on viral and non-viral gene therapy, as well as chemical inhibitors, for targeting TGFβ or downstream effectors in fibrotic disorders of the eye. Moreover, the role of angiogenetic and biomechanical factors in ocular fibrosis is discussed, focusing on related preclinical treatment approaches. Moreover, we describe available evidence on clinical studies investigating the use of therapies targeting TGFβ-dependent pathways, angiogenetic factors, and biomechanical factors, alone or in combination with other strategies, in ocular tissue fibrosis. Finally, the recent progress in cell-based therapies for treating fibrotic eye disorders is discussed. The increasing knowledge of these disorders in the eye and the promising results from testing of novel targeted therapies could offer viable perspectives for translation into clinical use.

Nerve Growth Factor-Based Therapy in Alzheimer's Disease and Age-Related Macular Degeneration

Alzheimer's disease (AD) is an age-associated neurodegenerative disease which is the most common cause of dementia among the elderly. Imbalance in nerve growth factor (NGF) signaling, metabolism, and/or defect in NGF transport to the basal forebrain cholinergic neurons occurs in patients affected with AD. According to the cholinergic hypothesis, an early and progressive synaptic and neuronal loss in a vulnerable population of basal forebrain involved in memory and learning processes leads to degeneration of cortical and hippocampal projections followed by cognitive impairment with accumulation of misfolded/aggregated Aβ and tau protein. The neuroprotective and regenerative effects of NGF on cholinergic neurons have been largely demonstrated, both in animal models of AD and in living patients. However, the development of this neurotrophin as a disease-modifying therapy in humans is challenged by both delivery limitations (inability to cross the blood-brain barrier (BBB), poor pharmacokinetic profile) and unwanted side effects (pain and weight loss). Age-related macular degeneration (AMD) is a retinal disease which represents the major cause of blindness in developed countries and shares several clinical and pathological features with AD, including alterations in NGF transduction pathways. Interestingly, nerve fiber layer thinning, degeneration of retinal ganglion cells and changes of vascular parameters, aggregation of Aβ and tau protein, and apoptosis also occur in the retina of both AD and AMD. A protective effect of ocular administration of NGF on both photoreceptor and retinal ganglion cell degeneration has been recently described. Besides, the current knowledge about the detection of essential trace metals associated with AD and AMD and their changes depending on the severity of diseases, either systemic or locally detected, further pave the way for a promising diagnostic approach. This review is aimed at describing the employment of NGF as a common therapeutic approach to AMD and AD and the diagnostic power of detection of essential trace metals associated with both diseases. The multiple approaches employed to allow a sustained release/targeting of NGF to the brain and its neurosensorial ocular extensions will be also discussed, highlighting innovative technologies and future translational prospects.

The mir-423-5p/MMP-2 Axis Regulates the Nerve Growth Factor-Induced Promotion of Chondrosarcoma Metastasis

Simple Summary

A chondrosarcoma is a common tumor of the bone that has a high propensity to metastasize to distant organs. The effects of NGF in a chondrosarcoma are not confirmed although NGF is capable of promoting the progression and metastasis of several different types of tumors. Here, we found that NGF promotes the chondrosarcoma migration and metastasis in vitro and in vivo. The levels of NGF and MMP-2 in human chondrosarcoma tumor tissues correlated strongly with the tumor stage. We identified that NGF induces the MMP-2 synthesis and chondrosarcoma cell motility by inhibiting miR-423-5p expression through the FAK and c-Src pathways. We suggest that NGF is a worthwhile therapeutic target in the treatment of a metastatic chondrosarcoma.

Abstract

A chondrosarcoma is a common tumor of the soft tissue and bone that has a high propensity to metastasize to distant organs. Nerve growth factor (NGF) is capable of promoting the progression and metastasis of several different types of tumors although the effects of NGF in a chondrosarcoma are not confirmed. Here, we found that the levels of NGF and matrix metalloproteinase-2 (MMP-2) correlated with the tumor stage in patients with a chondrosarcoma. NGF facilitated the MMP-2-dependent cellular migration in human chondrosarcoma JJ012 cells while the overexpression of NGF enhanced the lung metastasis in a mouse model of a chondrosarcoma. NGF promoted the MMP-2 synthesis and cell migration by inhibiting miR-423-5p expression through the FAK and c-Src signaling cascades. NGF appears to be a worthwhile therapeutic target in the treatment of a metastatic chondrosarcoma.

Overexpression of p75NTR in Human Seminoma: A New Biomarker?

Several studies have demonstrated that the p75NTR low-affinity receptor of Nerve Growth Factor (NGF), is produced in abnormally large amounts in several human cancer types. However, the role of p75NTR varies substantially depending on cell context, so that a dual role of this receptor protein in tumor cell survival and invasion, as well as cell death, has been supported in recent studies. Herein we explored for the first time the expression of p75NTR in human specimens (nr = 40) from testicular germ cell tumors (TGCTs), mostly seminomas. Nuclear overexpression of p75NTR was detected by immunohistochemistry in seminoma tissue as compared to normal tissue, whereas neither NGF nor its high-affinity TrkA receptor was detected. An increased nuclear staining of phospho-JNK, belonging to the p75NTR signaling pathway and its pro-apoptotic target gene, p53, was concomitantly observed. Interestingly, our analysis revealed that decreased expression frequency of p75NTR, p-JNK and p53 was related to staging progression, thus suggesting that p75NTR may represent a specific marker for seminoma and staging in TGCTs.

Role of NGF and its receptors in wound healing (Review)

Wound healing is an important and complicated process that includes four highly integrated and overlapping phases, haemostasis, inflammation, proliferation and tissue remodelling. Nerve growth factor (NGF) was the first member of a family of neurotrophic factors to be discovered, and is an essential neurotrophic factor for the development and maintenance of the central and peripheral nervous systems. Several studies have proposed that NGF and its receptors, tropomyosin-related kinase receptor 1 and NGF receptor, are involved in the wound healing process, and are important components of the healing of several wounds both in vivo and in vitro. Topical application of NGF significantly promotes the healing of different types of wounds, including diabetic foot ulcers, pressure ulcers and corneal wounds. The present review summarizes the status of NGF and its receptors in current literature, and discusses data obtained in the last few years on the healing action of NGF in cutaneous, corneal and oral wounds.

Possible involvement of neuropeptide and neurotransmitter receptors in Adenomyosis

BACKGROUND

Accumulating data indicate that sensory nerve derived neuropeptides such as substance P and calcitonin gene related-protein (CGRP) can accelerate the progression of endometriosis via their respective receptors, so can agonists to their respective receptors receptor 1 (NK1R), receptor activity modifying protein 1 (RAMP-1) and calcitonin receptor-like receptor (CRLR). Adrenergic β2 receptor (ADRB2) agonists also can facilitate lesional progression. In contrast, women with endometriosis appear to have depressed vagal activity, concordant with reduced expression of α7 nicotinic acetylcholine receptor (α7nAChR). The roles of these receptors in adenomyosis are completely unknown.

METHODS

Adenomyotic tissue samples from 30 women with adenomyosis and control endometrial tissue samples from 24 women without adenomyosis were collected and subjected to immunohistochemistry analysis of RAMP1, CRLR, NK1R, ADRB2 and α7nAChR, along with their demographic and clinical information. The extent of tissue fibrosis was evaluated by Masson trichrome staining.

RESULTS

We found that the staining levels of NK1R, CRLR, RAMP1 and ADRB2 were all significantly elevated in adenomyotic lesions as compared with control endometrium. In contrast, α7nAChR staining levels were significantly reduced. The severity of dysmenorrhea correlated positively with lesional ADRB2 staining levels.

CONCLUSIONS

Our results suggest that SP, CGRP and noradrenaline may promote, while acetylcholine may stall, the progression of adenomyosis through their respective receptors on adenomyotic lesions. Additionally, through the activation of the hypothalamic-pituitary-adrenal (HPA)-sympatho-adrenal-medullary (SAM) axes and the lesional overexpression of ADRB2, adenomyosis-associated dysmenorrhea and adenomyotic lesions may be mutually promotional, forming a viscous feed-forward cycle.

Macrophage-Derived Inflammation Induces a Transcriptome Makeover in Mesenchymal Stromal Cells Enhancing Their Potential for Tissue Repair

Pre-clinical and clinical studies revealed that mesenchymal stromal cell (MSC) transplants elicit tissue repair. Conditioning MSC prior to transplantation may boost their ability to support repair. We investigated macrophage-derived inflammation as a means to condition MSC by comprehensively analyzing their transcriptome and secretome. Conditioning MSC with macrophage-derived inflammation resulted in 3208 differentially expressed genes, which were annotated with significantly enriched GO terms for 1085 biological processes, 85 cellular components, and 79 molecular functions. Inflammation-mediated conditioning increased the secretion of growth factors that are key for tissue repair, including vascular endothelial growth factor, hepatocyte growth factor, nerve growth factor and glial-derived neurotrophic factor. Furthermore, we found that inflammation-mediated conditioning induces transcriptomic changes that challenge the viability and mobility of MSC. Our data support the notion that macrophage-derived inflammation stimulates MSC to augment their paracrine repair-supporting activity. The results suggest that inflammatory pre-conditioning enhances the therapeutic potential of MSC transplants.

NGF in Inflammatory and Neurodegenerative Diseases of the Eye: New Findings Supporting Neuroprotection and Proper Tissue Remodeling in Vitreoretinal Disorders

Nerve growth factor (NGF) plays a crucial role in retinal disorders, as suggested by in vitro/in vivo models. The major effect embraces the neuroprotective activity on retinal ganglion cells (RGCs) undergoing degeneration, as observed in experimental diabetic retinopathy, age-related and diabetic macular degeneration, and some vitreoretinal diseases. Focused experiments suggested that locally applied NGF (intravitreal delivery) not only allowed the counteraction of RGC degeneration but also provided data for a whole retina restoration. The currently available retinal microsurgery allows the collection of human aqueous and more interesting vitreous (vitreal reflux) humors. The recent biomolecular analysis highlights the possibility to identify disease-associated biomarkers and allow the monitoring of retinal impairments with sustain to the retinal imaging. Coupled to other soluble mediators, NGF has been quantified in aqueous (slightly expressed) from diabetic retinopathy-suffering patients (cataract surgery) and vitreal reflux (significantly impaired) of diabetic macular degeneration-suffering patients (intravitreal surgery). Although the reasons of these NGF impairments are not fully comprehended, some retinal cells (glial cells, bipolar neurons, and RGCs) have been recognized partially responsible for these local changes.Taken together, the recent progress in the ocular microsurgeries might be associated with sampling of small amount of ocular humors, allowing the collection of biochemical information about diseased retina and the monitoring of treatment. The chance to detect NGF and likewise other neuroprotective or pro-/anti-inflammatory factors in these fluids would open to the possibility to identify biomarkers of early diagnosis or monitoring of retinal disease evolution/therapy (precision medicine).

Nerve Growth Factor: The First Molecule of the Neurotrophin Family

Neurotrophins (NTs) are molecules regulating differentiation, maintenance, and functional plasticity of vertebrate nervous systems. Nerve growth factor (NGF) was the first to be identified in the neurotrophin family. The long scientific history of NTs provided not only advancement in the neuroscience field but opened new scenarios involving different body districts in physiological and pathological conditions, which include the immune, endocrine, and skeletal system, vascular districts, inflammation, etc. To date, many biological aspects of NTs have been clarified, but the new discoveries are still opening new insights on molecular and cellular mechanisms and systemic effects, also affecting the possible therapeutic application of NTs. This short review summarizes the main aspects of NGF biology and biochemistry, including the role of the NGF precursor molecule, high- and low-affinity receptors and related intracellular pathways, and target cells.

The Role of Hormones and Trophic Factors as Components of Preservation Solutions in Protection of Renal Function before Transplantation: A Review of the Literature

Transplantation is currently a routine method for treating end-stage organ failure. In recent years, there has been some progress in the development of an optimal composition of organ preservation solutions, improving the vital functions of the organ and allowing to extend its storage period until implantation into the recipient. Optimizations are mostly based on commercial solutions, routinely used to store grafts intended for transplantation. The paper reviews hormones with a potential nephroprotective effect, which were used to modify the composition of renal perfusion and preservation solutions. Their effectiveness as ingredients of preservation solutions was analysed based on a literature review. Hormones and trophic factors are innovative preservation solution supplements. They have a pleiotropic effect and affect normal renal function. The expression of receptors for melatonin, prolactin, thyrotropin, corticotropin, prostaglandin E1 and trophic factors was confirmed in the kidneys, which suggests that they are a promising therapeutic target for renal IR (ischemia-reperfusion) injury. They can have anti-inflammatory, antioxidant and anti-apoptotic effects, limiting IR injury.

Suprascapular nerve injury affects rotator cuff healing: A paired controlled study in a rat model

Purpose

We designed a paired controlled study to investigate the role of the suprascapular nerve (SSN) in rotator cuff healing using a rat tear model, and we hypothesised that rotator cuff healing is impaired in the absence of a healthy SSN.

Methods

Bilateral supraspinatus tenotomy from the great tuberosity was performed for 36 Wistar rats, which was then repaired immediately. A defect on the SSN was made on the right side, and a sham surgery was performed on the SSN at the left side. Twelve rats were sacrificed for biomechanical (six rats) and histological (six rats) testing, evaluated at 3, 6, and 9 weeks after surgery.

Results

The bone–tendon junction on the nerve-intact side showed significantly better biomechanical characteristics than the nerve-injured side in terms of maximum load, maximum stress over time, stiffness at 9 weeks, and Young's modulus at 3 and 9 weeks. On the nerve-injured side, significantly smaller fibrocartilage layers and muscle fibres could be obtained over time. In addition, on the nerve-injured side, inferior bone–tendon interface formation was obtained in terms of cell maturity, cell alignment, collagen orientation, and the occurrence of tidemark and Sharpey's fibres through 9 weeks. In addition, neuropeptide Y was secreted in the nerve-intact group at 6 and 9 weeks.

Conclusion

This study showed the inferior healing of the bone–tendon junction on the nerve-injured side compared with the nerve-intact side, which indicates that the SSN plays an important role in rotator cuff healing. Surgeons should pay more attention to SSN injury when treating patients with rotator cuff tear.

p75 neurotrophin receptor regulates NGF-induced myofibroblast differentiation and collagen synthesis through MRTF-A

Myofibroblasts are characterized by de novo expression of α-smooth muscle actin (α-SMA) and play a key role in tissue repair and remodeling. In addition to TGF-β1, recent studies have shown that nerve growth factor (NGF) has effects on myofibroblast differentiation and collagen synthesis. However, the regulatory mechanism remains poorly defined. NGF effects are mediated by the specific expression of the NGF neurotrophic tropomyosin-receptor kinase A (TrkA) and p75 neurotrophin receptor (p75NTR). Using NIH/3T3 fibroblast cell lines, we examined the induction of myofibroblast differentiation stimulated by NGF. Our findings showed that p75NTR was in keeping with the expression of α-SMA. Herein, we investigated the role of p75NTR in NGF-induced myofibroblast differentiation and collagen synthesis in these cells using lentivirus transfection to overexpress and knock down. Our results showed that p75NTR was preferentially expressed and was sufficient to induce actin cytoskeleton remodeling, which was required for NGF-induced α-SMA expression. Furthermore, NGF induced nuclear translocation of MRTF-A, an effect that was regulated by p75NTR, and required for α-SMA and collagen-I expression in myofibroblasts. Using a novel MRTF-A pathway inhibitor, CCG-203971, we further demonstrated the requirement of MRTF-A nuclear localization and activity in NGF-induced α-SMA expression. In conclusion, we conclude that p75NTR regulates NGF-induced myofibroblast differentiation and collagen synthesis through MRTF-A. Regulation of NGF-p75NTR interactions represents a promising therapy for fibrotic disorders.

Pre-treatment with Empagliflozin ameliorates Cisplatin induced acute kidney injury by suppressing apoptosis

Dose-limiting nephrotoxicity restricts Cisplatin use in high therapeutic doses. Empagliflozin showed a reno-protective effect in diabetic nephropathy. We investigated if Empagliflozin can ameliorate Cisplatin nephrotoxicity whether used prophylactically or therapeutically. Forty male Wistar rats were divided into 5 groups: (1) control; (2) Cisplatin-induced nephrotoxicity by single intraperitoneal dose; (3) Empagliflozin was given for 10 days before a single dose of Cisplatin; (4) a single dose of Cisplatin followed by Empagliflozin for 10 days; (5) received Empagliflozin only. Regular assessment of weight was done, biochemical evaluation for serum urea, creatinine, uric acid, albumin, and glucose was performed, kidney tissue nerve growth factor-β (NGF-β) and oxidative stress parameters were measured, kidneys were evaluated histopathologically and immunostained for caspase 3. Cisplatin significantly reduced body weight, NGF-β, and reduced glutathione, elevated urea, creatinine, and malondialdehyde with no effect on other serum biochemical parameters. Histopathologically, there was high acute tubular necrosis (ATN) score with strong immunostaining of caspase 3. The use of Empagliflozin significantly reduced urea and creatinine in both prophylactic and therapeutic, reduced ATN score in the prophylactic group associated with minimal staining of caspase 3 and elevated reduced glutathione. In conclusion, prophylactic Empagliflozin protected against Cisplatin-induced acute kidney injury mainly via anti-apoptotic effect.

The role of neurotrophins in psychopathology and cardiovascular diseases: psychosomatic connections

Cardiovascular (CV) diseases and mood disorders are common public health problems worldwide. Their connections are widely studied, and the role of neurotrophins (NTs) is already supposed in both conditions. However, data in the literature of clinical aspects are sometimes controversial and no reviews are available describing possible associations between CV risk and mood disorders based on NTs. The mostly studied NT is brain-derived neurotrophic factor (BDNF). Decreased level of BDNF is observed in depression and its connection to hypertension has also been demonstrated with affecting the arterial baroreceptors, renin–angiotensin system and endothelial nitric oxide synthase. BDNF was also found to be the predictor of CV outcome in different patient populations. Other types of human NT-s, such as nerve growth factor, neurotrophin 3 and neurotrophin 4 also seem to have both psychopathological and CV connections. Our aim was to overview the present knowledge in this area, demonstrating a new aspect of the associations between mood disorders and CV diseases through the mediation of NTs. These findings might enlighten new psychosomatic connections and suggest new therapeutic targets that are beneficial both in respect of mood disorders and CV pathology.

Tissue Engineering of Necrotic Dental Pulp of Immature Teeth with Apical Periodontitis in Dogs: Radiographic and Histological Evaluation

AIM

To evaluate tissue engineering technology to regenerate pulp-dentin like tissues in pulp canals of immature necrotic permanent teeth with apical periodontitis in dogs.

STUDY DESIGN

The study was performed on 36 teeth in 12 dogs. The experiment was carried out using split mouth design. In each dog 3 teeth were selected for implementing the study procedure. Apical periodontitis was induced in Group A and B teeth. Group (A): immature upper left 2^nd permanent incisors that were transplanted with a construct of autologous dental pulp stem cells with growth factors seeded in a chitosn hydrogel scaffold. Group (B): immature upper right 2^nd permanent incisor that received only growth factors with scaffold. A third tooth in each dog was selected randomly for isolation of dental pulp stem cells (DPSCs). Both groups were closed with a double coronal seal of white MTA (Mineral trioxide aggregate) and glass ionomer cement. Both groups were monitored radiographically for 4 months and histologically after sacrificing the animals.

RESULTS

There was no statistically significant difference in radiographic findings between group (A) and group (B) for healing of radiolucencies, while there was statistically significant difference between group (A) and group (B) regarding radicular thickening, root lengthening and apical closure. Histologically, group (A) teeth showed regeneration of pulp- dentin like tissue while group (B) teeth did not show any tissue regeneration.

CONCLUSION

Dental pulp stem cells and growth factors incorporated in chitosan hydrogel are able to regenerate pulp- dentine like tissue and help in complete root maturation of non-vital immature permanent teeth with apical periodontitis in dogs.

NGF and PI3K/Akt signaling participate in the ventral motor neuronal protection of curcumin in sciatic nerve injury rat models

OBJECTIVE

It has been reported that sciatic nerve injury (SNI) leads to degeneration, damage, and apoptosis of motor neurons. Nerve growth factor (NGF) plays a pivotal role in regeneration and reestablishment of neuronal function via activating PI3K/Akt survival signaling pathways. Curcumin owns neuroprotective effect following brain injury. In the present study, we attempt to investigate underlying mechanism of neuroprotective effect of curcumin through elucidating its correlation with NGF and PI3K/Akt signaling pathways in vitro and in vivo.

METHODS

PC-12 cells were exposed H₂O₂ in order to induce neuron cell injury and cells were then treated with curcumin. Caspase-3, NGF level and Akt phosphorylation were determined using flow cytometry and western blotting. Then, cells were treated with NGF specific siRNA followed by measurement of apoptosis, NGF and Akt phosphorylation levels. In animal model, rats were subjected to SNI and then randomly designated into four different groups: curcumin, curcumin + LY294002, curcumin + NGF shRNA, and negative controls and 12 rats in each group (n = 12). After four weeks of continuous treatment, tissue samples were obtained and subjected to TUNEL, NeuN double staining and western blotting.

RESULTS

Curcumin significantly reduced the number of apoptotic cells induced by H₂O₂ and this effect was associated with upregulation of TrkA, Akt and downregulation of p17. ProNGF level was significantly decreased while mature NGF level was increased with curcumin treatment. When NGF was suppressed, anti-apoptotic effect of curcumin was attenuated. In addition, inhibition of PI3K/Akt results in increased apoptotic rate compared to vehicles following curcumin treatment which was reflected by decreased p17, Ki67, and cyclin D1. Suppression of NGF and inhibition of PI3K led to increased neuron cell death through increasing proNGF and decreasing mNGF, Akt, TrkA, p75^NTR, and p17.

CONCLUSION

Our findings revealed that curcumin exerts its protective effect against injured neurons through stimulating NGF release which further activates TrkA and PI3K/Akt cell survival signaling.

Long-Term Non-Invasive Treatment via Intranasal Administration of Nerve Growth Factor Protects the Human Brain in Frontotemporal Dementia associated with Corticobasal Syndrome: A Pilot Study

Background:

Nerve growth factor (NGF) is known for playing a critical protective role on a number of brain neurons in mammals, including humans. NGF can be delivered to the CNS via nasal route and has a neuroprotective action in case of neurodegenerative diseases.

Objective:

The aim of this study is to investigate for the first time whether purified NGF can play a neuroprotective role on human brain neurons affected by neurodegenerative diseases when administered via nasal route.

Methods:

Two female patients, both affected by frontotemporal dementia (FTD) associated with corticobasal syndrome (CBS) at different stages of disease progression, received a daily intranasal NGF spray for one year. Clinical/neurological aspects were observed over time. The follow-up study was performed using 18 FDG PET.

Results:

This case study seems to demonstrate that IN-NGF slows down the common decline caused by FTD/CBS.

Conclusions:

These findings suggest the potential neuroprotective role of IN-NGF administered in case of neurodegenerative diseases.

Effect of laser therapy on expression of angio- and fibrogenic factors, and cytokine concentrations during the healing process of human pressure ulcers

Objective: To evaluate the effect of laser irradiation at different wavelengths on the expression of selected growth factors and inflammatory mediators at particular stages of the wound healing process. Methods: Sixty-seven patients were recruited, treated, and analyzed (group A - 940 nm: 17 patients; group B - 808 nm: 18 patients; group C - 658 nm: 16 patients; group D - sham therapy: 17 patients). Patients received a basic treatment, including repositioning and mobilization, air pressure mattress and bed support surfaces, wound cleansing and drug therapy. Additionally, patients received laser therapy once a day, 5 times a week for 1 month in use of a semiconductor lasers (GaAlAs) which emitted a continuous radiation emission at separate wavelengths of 940 nm (group A), 808 nm (group B) and 658 nm (group C). In group D (sham therapy), laser therapy was applied in the same manner, but the device was off during each session (only the applicator was switched on to scan pressure ulcers using none coherent red visible light). Results: The positive changes in the measured serum (IL-2, IL-6 and TNF-α) and wound tissue (TNF-α, VEGF and TGFβ1) parameters appeared to be connected only with the wavelength of 658 nm. The significant change in pro-inflammatory mediator levels [interleukin 2 (IL-2) with p=0.008 and interleukin 6 (IL-6) with p=0.016] was noticed after two weeks of laser therapy. In the other groups, the inflammation was also reduced, but the process was not as marked as in group C. Similarly, in the case of tumor necrosis factor (TNF-α) concentration, where after two weeks of treatment with irradiation at a wavelength of 658 nm, a rapid suppression was observed (p=0.001), whereas in the other groups, these results were much slower and not as obvious. Interestingly, again in the case of group C, the change in TNF-α concentration in wound tissue was most intensive (≈75% reduction), whereas the changes in other groups were not as obvious (≈50% reduction). After irradiation (658 nm), the VEGF expression increased significantly within the first two weeks, and then it decreased and maintained a stable level. In contrast, the TGFβ1 activity remained level, but always higher in comparison to other groups Conclusions: The effective healing of pressure ulcers is connected with laser irradiation at a wavelength of 658 nm. We believe that this effect is related to the inhibition of inflammatory processes in the wound and stimulation of angiogenesis and fibroblast proliferation at this specific radiation (based both on concentration of interleukins and TNF-α serum level and VEGF, TGFβ1, TNF-α activities in wound biopsies). Laser therapy at wavelengths of 940 and 808 nm does not significantly affect the above-mentioned repair processes, which explains its low effectiveness in the treatment of pressure ulcers.

The Role of Nerve Growth Factor (NGF) and Its Precursor Forms in Oral Wound Healing

Nerve growth factor (NGF) and its different precursor forms are secreted into human saliva by salivary glands and are also produced by an array of cells in the tissues of the oral cavity. The major forms of NGF in human saliva are forms of pro-nerve growth factor (pro-NGF) and not mature NGF. The NGF receptors tropomyosin-related kinase A (TrkA) and p75 neurotrophin receptor (p75^NTR) are widely expressed on cells in the soft tissues of the human oral cavity, including keratinocytes, endothelial cells, fibroblasts and leukocytes, and in ductal and acinar cells of all types of salivary glands. In vitro models show that NGF can contribute at most stages in the oral wound healing process: restitution, cell survival, apoptosis, cellular proliferation, inflammation, angiogenesis and tissue remodeling. NGF may therefore take part in the effective wound healing in the oral cavity that occurs with little scarring. As pro-NGF forms appear to be the major form of NGF in human saliva, efforts should be made to study its function, specifically in the process of wound healing. In addition, animal and clinical studies should be initiated to examine if topical application of pro-NGF or NGF can be a therapy for chronic oral ulcerations and wounds.

Exploring Serum Levels of Brain Derived Neurotrophic Factor and Nerve Growth Factor Across Glaucoma Stages

Purpose

To investigate the serum levels of Brain Derived Neurotrophic Factor (BDNF) and Nerve Growth Factor (NGF) in patients affected by primary open angle glaucoma with a wide spectrum of disease severity compared to healthy controls and to explore their relationship with morphological and functional glaucoma parameters.

Materials and Methods

45 patients affected by glaucoma at different stages and 15 age-matched healthy control subjects underwent visual field testing, peripapillary retinal nerve fibre layer thickness measurement using Spectral Domain Optical Coherence Tomography and blood collection for both neurotrophins detection by Enzyme-Linked Immunosorbent Assay. Statistical analysis and association between biostrumental and biochemical data were investigated.

Results

Serum levels of BDNF in glaucoma patients were significantly lower than those measured in healthy controls (261.2±75.0 pg/ml vs 313.6±79.6 pg/ml, p = 0.03). Subgroups analysis showed that serum levels of BDNF were significantly lower in early (253.8±40.7 pg/ml, p = 0.019) and moderate glaucoma (231.3±54.3 pg/ml, p = 0.04) but not in advanced glaucoma (296.2±103.1 pg/ml, p = 0.06) compared to healthy controls.

Serum levels of NGF in glaucoma patients were significantly lower than those measured in the healthy controls (4.1±1 pg/mL vs 5.5±1.2 pg/mL, p = 0.01). Subgroups analysis showed that serum levels of NGF were significantly lower in early (3.5±0.9 pg/mL, p = 0.0008) and moderate glaucoma (3.8±0.7 pg/ml, p<0.0001) but not in advanced glaucoma (5.0±0.7 pg/ml, p = 0.32) compared to healthy controls.

BDNF serum levels were not related to age, visual field mean deviation or retinal nerve fibre layer thickness either in glaucoma or in controls while NGF levels were significantly related to visual field mean deviation in the glaucoma group (r² = 0.26, p = 0.004).

Conclusions

BDNF and NGF serum levels are reduced in the early and moderate glaucoma stages, suggesting the possibility that both factors could be further investigated as potential circulating biomarkers for the early detection of glaucoma.

The Potential of Combination Therapeutics for More Complete Repair of Volumetric Muscle Loss Injuries: The Role of Exogenous Growth Factors and/or Progenitor Cells in Implantable Skeletal Muscle Tissue Engineering Technologies

Despite the robust regenerative capacity of skeletal muscle, there are a variety of congenital and acquired conditions in which the volume of skeletal muscle loss results in major permanent functional and cosmetic deficits. These latter injuries are referred to as volumetric muscle loss (VML) injuries or VML-like conditions, and they are characterized by the simultaneous absence of multiple tissue components (i.e., nerves, vessels, muscles, satellite cells, and matrix). There are currently no effective treatment options. Regenerative medicine/tissue engineering technologies hold great potential for repair of these otherwise irrecoverable VML injuries. In this regard, three-dimensional scaffolds have been used to deliver sustained amounts of growth factors into a variety of injury models, to modulate host cell recruitment and extracellular matrix remodeling. However, this is a nascent field of research, and more complete functional improvements require more precise control of the spatiotemporal distribution of critical growth factors over a physiologically relevant range. This is especially true for VML injuries where incorporation of a cellular component into the scaffolds might provide not only a source of new tissue formation but also additional signals for host cell migration, recruitment, and survival. To this end, we review the major features of muscle repair and regeneration for largely recoverable injuries, and then discuss recent cell- and/or growth factor-based approaches to repair the more profound and irreversible VML and VML-like injuries. The underlying supposition is that more rationale incorporation of exogenous growth factors and/or cellular components will be required to optimize the regenerative capacity of implantable therapeutics for VML repair.

Nerve Growth Factor: A Focus on Neuroscience and Therapy

Nerve growth factor (NGF) is the firstly discovered and best characterized neurotrophic factor, known to play a critical protective role in the development and survival of sympathetic, sensory and forebrain cholinergic neurons. NGF promotes neuritis outgrowth both in vivo and in vitro and nerve cell recovery after ischemic, surgical or chemical injuries. Recently, the therapeutic property of NGF has been demonstrated on human cutaneous and corneal ulcers, pressure ulcer, glaucoma, maculopathy and retinitis pigmentosa. NGF eye drops administration is well tolerated, with no detectable clinical evidence of systemic or local adverse effects. The aim of this review is to summarize these biological properties and the potential clinical development of NGF.

Nerve growth factor: role in growth, differentiation and controlling cancer cell development

Recent progress in the Nerve Growth Factor (NGF) research has shown that this factor acts not only outside its classical domain of the peripheral and central nervous system, but also on non-neuronal and cancer cells. This latter observation has led to divergent hypothesis about the role of NGF, its specific distribution pattern within the tissues and its implication in induction as well as progression of carcinogenesis. Moreover, other recent studies have shown that NGF has direct clinical relevance in certain human brain neuron degeneration and a number of human ocular disorders. These studies, by suggesting that NGF is involved in a plethora of physiological function in health and disease, warrant further investigation regarding the true role of NGF in carcinogenesis. Based on our long-lasting experience in the physiopathology of NGF, we aimed to review previous and recent in vivo and in vitro NGF studies on tumor cell induction, progression and arrest. Overall, these studies indicate that the only presence of NGF is unable to generate cell carcinogenesis, both in normal neuronal and non-neuronal cells/tissues. However, it cannot be excluded the possibility that the co-expression of NGF and pro-carcinogenic molecules might open to different consequence. Whether NGF plays a direct or an indirect role in cell proliferation during carcinogenesis remains to demonstrate.

NGF Modulates trkANGFR/p75NTR in αSMA-Expressing Conjunctival Fibroblasts from Human Ocular Cicatricial Pemphigoid (OCP)

Objective

In a previous study, we reported the upregulation of Nerve Growth Factor (NGF) and trkA^NGFR expression in Ocular Cicatricial Pemphigoid (OCP), an inflammatory and remodeling eye disease. Herein, we hypothesize a potential NGF-driven mechanism on fibroblasts (FBs) during OCP remodeling events. To verify, human derived OCP-FBs were isolated and characterized either at baseline or after NGF exposure.

Materials and Methods

Conjunctival biopsies were obtained from 7 patients having OCP and 6 control subjects (cataract surgery). Both conjunctivas and primary FB cultures were characterised for αSMA, NGF and trkA^NGFR/p75^NTR expression. Subcultures were exposed to NGF and evaluated for αSMA, NGF, trkA^NGFR/p75^NTR expression as well as TGFβ1/IL4 release. For analysis, early and advanced subgroups were defined according to clinical parameters.

Results

OCP-conjunctivas showed αSMA-expressing FBs and high NGF levels. Advanced OCP-FBs showed higher αSMA expression associated with higher p75^NTR and lower trkA^NGFR expression, as compared to early counterparts. αSMA expression was in keeping with disease severity and correlated to p75^NTR. NGF exposure did not affect trkA^NGFR levels in early OCP-FBs while decreased both αSMA/p75^NTR expression and TGFβ1/IL4 release. These effects were not observed in advanced OCP-FBs.

Conclusions

Taken together, these data are suggestive for a NGF/p75^NTR task in the potential modulation of OCP fibrosis and encourages further studies to fully understand the underlying mechanism occurring in fibrosis. NGF/p75^NTR might be viewed as a potential therapeutic target.

The Effects of Generally Administered Anti-Nerve Growth Factor Receptor (p75NTR) Antibody on Pain-Related Behavior, Dorsal Root Ganglia, and Spinal Glia Activation in a Rat Model of Brachial Plexus Avulsion

PURPOSE

To investigate the effect of intraperitoneal administration of an anti-p75 neurotrophin receptor (p75NTR) antibody on reducing neuropathic pain in a rat model of brachial plexus avulsion (BPA).

METHODS

We randomly assigned 40 male Wistar rats to 4 groups. In the BPA group, the C8-T1 roots were avulsed from the spinal cord at the lower trunk level, and saline was administered intraperitoneally. In the anti-p75NTR groups, 1 μL or 50 μL anti-p75NTR antibody was administered intraperitoneally after avulsion. In the sham-operated group, the lower trunk level was exposed, and saline was administered intraperitoneally. Mechanical hyperalgesia and pain-induced walking patterns were measured using von Frey filaments and CatWalk gait analysis at various time points until 15 days after administration. At 3 and 15 days after administration, sensory neurons involved in pain perception and satellite glial cells in the ipsilateral C7 dorsal root ganglia were immunolabeled with antibodies against calcitonin gene-related peptide and glial fibrillary acidic protein (GFAP), respectively. At both time points, microglial and astrocyte activation, indicative of spinal pain transmission, were immunohistochemically examined in the ipsilateral dorsal horn of the spinal cord (C7) using anti-ionized calcium-binding adaptor molecule 1 and anti-GFAP antibodies, respectively.

RESULTS

The gait pattern was significantly improved in both anti-p75NTR groups compared with the BPA group. There were significantly fewer calcitonin gene-related peptide-immunoreactive (IR) neurons, neurons encircled by GFAP-IR satellite glial cells, and GFAP-IR astrocytes in both anti-p75NTR groups compared with the BPA group at both time points. Fewer ionized calcium-binding adaptor molecule 1-IR microglia were quantified in both anti-p75NTR groups compared with the BPA group, but this was only significant at 15 days after administration.

CONCLUSIONS

Systemic application of the p75NTR inhibitory antibody suppressed neuropathic pain after BPA.

CLINICAL RELEVANCE

p75NTR may be a potential therapeutic target for the clinical treatment of neuropathic pain in BPA injury.

NGF Expression in Reelin-Deprived Retinal Cells: A Potential Neuroprotective Effect

We recently reported that increased NGF and p75(NTR) as well as decreased trkA(NGFR) characterized the Reelin-deprived (E-Reeler) retina, prospecting a potential contribution of NGF during E-Reeler retinogenesis. Herein, retinal ganglion cells (RGCs), glial cells and rod bipolar cells (RBCs) were isolated from E-Reeler retinas, and NGF, trkA(NGFR)/p75(NTR) expression and apoptosis were investigated. E-Reeler (n = 28) and E-control (n = 34) retinas were digested, and RGCs, glial cells and RBCs were isolated by the magnetic bead separation. Expression of NGF, trkA(NGFR), p75(NTR), Annexin V/PI and Bcl2/Bax was quantified by flow cytometry and validated by real-time PCR or WB. In E-Reeler retinas, NGF was significantly increased in RGCs and glial cells, p75(NTR) was increased in both RBCs and RGCs, and trkA(NGFR) was unchanged. In E-control retinas, NGF and p75(NTR) were expressed mainly in RBCs and RGCs and faintly in glial cells, while trkA(NGFR) was weakly expressed by RBCs and RGCs. In RBCs and RGCs, Annexin V expression was unchanged, while Bcl2 increased and Bax decreased selectively in E-Reeler RGCs. The data indicate that E-Reeler RBCs and RGCs overexpress NGF and p75(NTR) as a protective endogenous response to Reelin deprivation. The observation is strongly supported by the absence of apoptosis in both cell types.

Effect of purified murine NGF on isolated photoreceptors of a rodent developing retinitis pigmentosa

A number of different studies have shown that neurotrophins, including nerve growth factor (NGF) support the survival of retinal ganglion neurons during a variety if insults. Recently, we have reported that that eye NGF administration can protect also photoreceptor degeneration in a mice and rat with inherited retinitis pigmentosa. However, the evidence that NGF acts directly on photoreceptors and that other retinal cells mediate the NGF effect could not be excluded. In the present study we have isolated retinal cells from rats with inherited retinitis pigmentosa (RP) during the post-natal stage of photoreceptor degenerative. In presence of NGF, these cells are characterized by enhanced expression of NGF-receptors and rhodopsin, the specific marker of photoreceptor and better cell survival, as well as neuritis outgrowth. Together these observations support the hypothesis that NGF that NGF acts directly on photoreceptors survival and prevents photoreceptor degeneration as previously suggested by in vivo studies.

Nerve growth factor exposure promotes tubular epithelial-mesenchymal transition via TGF-β1 signaling activation

Clinical studies showed that renal expression and serum levels of nerve growth factor (NGF) are increased in renal diseases characterized by progressive fibrosis, a pathologic process in which TGF-β1 mediates most of the key events leading to tubular epithelial-mesenchymal transition (EMT). However, the pathogenic role of high NGF levels has not yet been elucidated. In this study, we found that in tubular renal cells, HK-2, NGF transcriptionally up-regulated TGF-β1 expression and secretion and enhanced cell motility by activating EMT markers via its receptors, TrkA and p75(NTR). Interestingly, we observed that TGF-β1-SMAD pathway activation and the up-regulation of EMT markers NGF-induced were both prevented when knockdown of TGF-β1 gene occurred and that the pretreatment with an antibody anti-NGF reversed the nuclear translocation of pSMAD3/SMAD4 complex. Collectively, our results demonstrated that NGF promotes renal fibrosis via TGF-β1-signaling activation, suggesting that in kidney diseases high NGF serum levels could contribute to worsen renal fibrosis.

A comparative analysis of the structural, functional and biological differences between Mouse and Human Nerve Growth Factor

NGF is the prototype member of the neurotrophin family of proteins that promote the survival and growth of selected neurons in the central and peripheral nervous systems. As for all neurotrophins, NGF is translated as a pre-pro-protein. Over the years, NGF and proNGF of either human or mouse origin, given their high degree of homology, have been exploited for numerous applications in biomedical sciences. The mouse NGF has been considered the golden-standard for bioactivity. Indeed, due to evolutionary relatedness to human NGF and to its ready availability and by assuming identical properties to its human counterpart, the mouse NGF, isolated and purified from sub-maxillary glands, has been tested not only in laboratory practice and in preclinical models, but it has also been evaluated in several human clinical trials. Aiming to validate this assumption, widely believed, we performed a comparative study of the biochemical and biophysical properties of the mouse and human counterparts of NGF and proNGF. The mature and the precursor proteins of either species strikingly differ in their biophysical profiles and, when tested for ligand binding to their receptors, in their in vitro biological activities. We provide a structural rationale that accounts for their different functional behaviors. Despite being highly conserved during evolution, NGF and proNGF of mouse and human origins show distinct properties and therefore special care must be taken in performing experiments with cross-species systems in the laboratory practice, in developing immunoassays, in clinical trials and in pharmacological treatments.

Nerve growth factor increases MMP9 activity in annulus fibrosus cells by upregulating lipocalin 2 expression

PURPOSE

Nerve growth factor (NGF) expression and activity is important in chronic lower back pain but may also act as a pro-catabolic factor in the pathogenesis of intervertebral disc (IVD) degeneration. Lipocalin 2 (Lcn2) expression in IVD was upregulated by NGF stimulation in our previous study. The current study was undertaken to identify potential mechanisms of the latter effect including potential interactions between Lcn2 and matrix metalloproteinase 9 (MMP9).

METHODS

Rat annulus fibrosus (AF) cells were stimulated by NGF and subjected to microarray analysis, subsequent real-time PCR, western immunoblotting, and immunofluorescence. Cells were treated with NGF in the absence or presence of the NGF inhibitor Ro 08-2750. Zymography and functional MMP9 assays were used to determine MMP9 activity, whilst the dimethyl-methylene blue assay was used to quantify the release of glycosaminoglycans (GAGs) reflecting catabolic effects following NGF treatment. Immunoprecipitation with immunoblotting was used to identify interactions between MMP9 and Lcn2.

RESULTS

Increased expression of Lcn2 gene and protein following NGF stimulation was confirmed by microarray analysis, real-time PCR, western blot and immunofluorescence. Zymography showed that NGF enhanced 125-kDa gelatinase activity, identified as a Lcn2/MMP9 complex by immunoprecipitation and immunoblotting. Functional assays showed increased MMP9 activity and GAG release in the presence of NGF. The effects of NGF were neutralized by the presence of Ro 08-2750.

CONCLUSIONS

NGF upregulates Lcn2 expression and increases MMP9 activity in AF cells; processes which are likely to potentiate degeneration of AF tissue in vivo. Anti-NGF treatment may have benefit for management of pain relief and slowing down progression of AF tissue degeneration.

Nerve growth factor promotes expression of novel genes in intervertebral disc cells that regulate tissue degradation

Object

Increased neurotrophin activity in degenerative intervertebral discs (IVDs) is one potential cause of chronic low-back pain (LBP). The aim of the study was to assess if nerve growth factor (NGF) might alter gene expression of IVD cells and contribute to disc degeneration by enhancing expression or activity of factors that cause breakdown of IVD matrix.

Methods

Rat-tail IVD cells were stimulated by NGF and subjected to microarray analysis. Real-time polymerase chain reaction, Western blotting, and immunocytochemistry of rat and human IVD cells and tissues treated with NGF in vitro in the absence or presence of the NGF inhibitor Ro 08-2750 were used to confirm findings of the microarray studies. Phosphorylation of mitogen-activated protein kinase (MAPK) was used to identify cell signaling pathways involved in NGF stimulation in the absence or presence of Ro 08-2750.

Results

Microarray analysis demonstrated increased expression of chitinase 3-like 1 (Chi3l1), lipocalin 2 (Lcn2), and matrix metalloproteinase–3 (Mmp3) following NGF stimulation of rat IVD cells in vitro. Increased gene expression was confirmed by real-time polymerase chain reaction with a relative increase in the Mmp/Timp ratio. Increased expression of Chi3l1, Lcn2, and Mmp3 following NGF stimulation was also demonstrated in rat cells and human tissue in vitro. Effects of NGF on protein expression were blocked by an NGF inhibitor and appear to function through the extracellular-regulation kinase 1/2 (ERK1/2) MAPK pathway.

Conclusions

Nerve growth factor has potential effects on matrix turnover activity and influences the catabolic/anabolic balance of IVD cells in an adverse way that may potentiate IVD degeneration. Anti-NGF treatment might be beneficial to ameliorate progressive tissue breakdown in IVD degeneration and may lead to pain relief.

Mechanical tension promotes skin nerve regeneration by upregulating nerve growth factor expression

This study aimed to explore the role of mechanical tension in hypertrophic scars and the change in nerve density using hematoxylin-eosin staining and S100 immunohistochemistry, and to observe the expression of nerve growth factor by western blot analysis. The results demonstrated that mechanical tension contributed to the formation of a hyperplastic scar in the back skin of rats, in conjunction with increases in both nerve density and nerve growth factor expression in the scar tissue. These experimental findings indicate that the cutaneous nervous system plays a role in hypertrophic scar formation caused by mechanical tension.

Up-regulation of Glutamate in Painful Human Supraspinatus Tendon Tears

BACKGROUND

Pain related to rotator cuff tendinopathy is a common problem, but little is known regarding the origin and cause of pain from the tendon substance. No study to date has looked at the association between tissue changes and patient outcomes.

PURPOSE

To describe the peripheral neuronal phenotype in painful rotator cuff tears and to determine correlations between tissue changes and clinical outcome measures.

STUDY DESIGN

Controlled laboratory study.

METHODS

Tissue samples of the supraspinatus were taken from patients undergoing surgery to repair a rotator cuff tendon tear. Patients were classified as having small/medium or large/massive tears. Control tissue was obtained from patients undergoing surgery for posttraumatic shoulder instability. Immunohistochemical techniques were performed using antibodies to known nociceptive and neuronal markers as well as general tissue structural markers.

RESULTS

There was no correlation between tissue changes and patient-reported outcomes. A significant increase in the expression of glutamate was seen in tendon tears. There were differences in the expression of metabotropic and ionotropic glutamate receptors. Expression changes were also observed for markers of the sensory and autonomic systems; however, no differences were found in neurotrophins.

CONCLUSION

Glutamate and the glutaminergic system play a key role in painful human tendon tears; however, the exact role is still uncertain, as glutamate is highly involved in both pain and metabolic pathways.

CLINICAL RELEVANCE

This study has identified a number of markers that could be potential therapeutic targets.

The potential of dental stem cells differentiating into neurogenic cell lineage after cultivation in different modes in vitro

Trauma or degenerative diseases of the central nervous system (CNS) cause the loss of neurons or glial cells. Stem cell transplantation has become a vital strategy for CNS regeneration. It is necessary to effectively induce nonneurogenic stem cells to differentiate into neurogenic cell lineages because of the limited source of neurogenic stem cells, relatively difficult cultivation, and ethical issues. Previous studies have found that dental stem cells can be used for transplantation therapy. The aim of this study was to explore a better inductive mode and time point for dental stem cells to differentiate into neural-like cells and evaluate a better candidate cell. In this study, dental follicle stem cells (DFSCs), dental papilla stem cells (DPSCs), and stem cells from apical papilla (SCAPs) were cultivated in five different modes. The proliferation ability, morphology, and expression of neural marker genes were analyzed. Results showed that DFSCs showed a higher proliferation potential. The proliferation was decreased after cultivation in chemical inductive medium as cultivation modes 3 and 5. The cells could present neural-like cell morphology after cultivation with human epidermal growth factor (EGF) and fibroblast growth factor-basic (bFGF) as cultivation modes 4 and 5. The vast majority of DFSCs gene expression levels in mode 4 on the third day was upregulated significantly. In conclusion, our data suggested that different dental stem cells exhibited different neural differentiation potentials. DFSCs might be the better candidate cell type. Furthermore, cultivation mode 4 and timing of the third day may promote differentiation into neurogenic cell lineages more effectively before transplantation to treat neurological diseases.

Evidence for bladder urothelial pathophysiology in functional bladder disorders

Understanding of the role of urothelium in regulating bladder function is continuing to evolve. While the urothelium is thought to function primarily as a barrier for preventing injurious substances and microorganisms from gaining access to bladder stroma and upper urinary tract, studies indicate it may also function in cell signaling events relating to voiding function. This review highlights urothelial abnormalities in bladder pain syndrome/interstitial cystitis (BPS/IC), feline interstitial cystitis (FIC), and nonneurogenic idiopathic overactive bladder (OAB). These bladder conditions are typified by lower urinary tract symptoms including urinary frequency, urgency, urgency incontinence, nocturia, and bladder discomfort or pain. Urothelial tissues and cells from affected clinical subjects and asymptomatic controls have been compared for expression of proteins and mRNA. Animal models have also been used to probe urothelial responses to injuries of the urothelium, urethra, or central nervous system, and transgenic techniques are being used to test specific urothelial abnormalities on bladder function. BPS/IC, FIC, and OAB appear to share some common pathophysiology including increased purinergic, TRPV1, and muscarinic signaling, increased urothelial permeability, and aberrant urothelial differentiation. One challenge is to determine which of several abnormally regulated signaling pathways is most important for mediating bladder dysfunction in these syndromes, with a goal of treating these conditions by targeting specific pathophysiology.

Characterization of NGF, trkA (NGFR) , and p75 (NTR) in Retina of Mice Lacking Reelin Glycoprotein

Both Reelin and Nerve Growth Factor (NGF) exert crucial roles in retinal development. Retinogenesis is severely impaired in E-reeler mice, a model of Reelin deficiency showing specific Green Fluorescent Protein expression in Rod Bipolar Cells (RBCs). Since no data are available on Reelin and NGF cross-talk, NGF and trkA^NGFR/ p75^NTR expression was investigated in retinas from E-reeler versus control mice, by confocal microscopy, Western blotting, and real time PCR analysis. A scattered increase of NGF protein was observed in the Ganglion Cell Layer and more pronounced in the Inner Nuclear Layer (INL). A selective increase of p75^NTR was detected in most of RBCs and in other cell subtypes of INL. On the contrary, a slight trend towards a decrease was detected for trkA^NGFR, albeit not significant. Confocal data were validated by Western blot and real time PCR. Finally, the decreased trkA^NGFR/ p75^NTR ratio, representative of p75^NTR increase, significantly correlated with E-reeler versus E-control. These data indicate that NGF-trkA^NGFR/ p75^NTR is affected in E-reeler retina and that p75^NTR might represent the main NGF receptor involved in the process. This first NGF-trkA^NGFR/ p75^NTR characterization suggests that E-reeler might be suitable for exploring Reelin-NGF cross-talk, representing an additional information source in those pathologies characterized by retinal degeneration.