Receptor P75 Research Articles

Plateau hypoxia-induced upregulation of reticulon 4 pathway mediates altered autophagic flux involved in blood-brain barrier disruption after traumatic brain injury.

This study aimed to examine reticulon 4 (RTN4), neurite outgrowth inhibitor protein expression that changes in high-altitude traumatic brain injury (HA-TBI) and affects on blood-brain barrier's (BBB) function. C57BL/6J 6-8-week-old male mice were used for TBI model induction and randomized into the normal altitude group and the 5000-m high-altitude (HA) group, each group was divided into control (C) and 8h/12h/24h/48h-TBI according to different times post-TBI. Brain water content (BWC) and modified Neurological Severity Score were measured, RTN4 and autophagy-related indexes (Beclin1, LC3B, and SQSTM1/p62) were detected by western blot, immunofluorescence technique, and PCR in peri-injury cortical tissues. The expression of NgR1, Lingo-1, TROY, P75, PirB, S1PR2, and RhoA receptors' downstream of RTN4 was detected by PCR. HA-TBI caused increased neurological deficits including motor, sensory, balance and reflex deficits, increased BWC, earlier peak RTN4 expression and a longer duration of high expression in peri-injury cortical tissues, and enhanced levels of Beclin1, LC3B, and SQSTM1/p62 to varying degrees. Concurrently, the transcription of S1PR2 and PirB, the main signaling molecules downstream of RTN4, was significantly increased. In HA-TBI's early stages, the increased RTN4 may regulate enhanced autophagic initiation and impaired autolysosome degradation in vascular endothelial cells via S1PR2 receptor activation, thereby reducing BBB function. This suggests that autophagy could be a new target using RTN4 intervention as a clinical HA-TBI mechanism.

Targeting nerve growth factor for pain relief: pros and cons.

Nerve growth factor (NGF) is a neurotrophic protein that has crucial roles in survival, growth and differentiation. It is expressed in neuronal and non-neuronal tissues. NGF exerts its effects via two types of receptors including the high affinity receptor, tropomyosin receptor kinase A and the low affinity receptor p75 neurotrophin receptor highlighting the complex signaling pathways that underlie the roles of NGF. In pain perception and transmission, multiple studies shed light on the effects of NGF on different types of pain including inflammatory, neuropathic, cancer and visceral pain. Also, the binding of NGF to its receptors increases the availability of many nociceptive receptors such as transient receptor potential vanilloid 1, transient receptor potential ankyrin 1, N-methyl-D-aspartic acid, and P2X purinoceptor 3 as well as nociceptive transmitters such as substance P and calcitonin gene-related peptide. The role of NGF in pain has been documented in pre-clinical and clinical studies. This review aims to shed light on the role of NGF and its signaling in different types of pain.

Molecular signaling of key neurotrophic factors in the brain while the occurrence of affective disorders

The COVID-19 pandemic and the increasingly tense political situation worldwide have led to an increase in the incidence of mood disorders. The occurrence of affective disorders is usually associated with neurotransmitters such as serotonin and dopamine; however, modern trends aim at studying the involvement of neurotrophic factors in the mechanisms of mood disorders. This review aimed to summarize and systematize knowledge about key neurotrophic factors and the molecular mechanisms of their relationships. The key metabolic mechanisms of proteins such as brain-derived neurotrophic factor, vascular endothelial growth factor, insulin-like growth factor-1, basic fibroblast growth factor-2, nerve growth factor, and glial cell-line derived neurotrophic factor are considered. Molecular pathways were analyzed, and a complex diagram of a multiple cascade with interconnected reactions was compiled, including each factor. Key molecular targets chosen included nuclear factor kappa-light-chain-enhancer of activated B-cells (NF-kB) and cAMP response element-binding protein. The review also presented candidates for the role of limiting factors for these molecular targets. For the NF-kB cascade, neurotrophin receptor p75(NTR) was proposed as a limiting factor, and those for the CREB cascade were intracellular phospholipase C (PLC-γ), binary molecular switches (RAS-GTP), and protein kinase B (AKT).

BDNF prodomain inhibits neurotransmitter quantal release in mouse motor synapses with the necessary participation of sortilin and adenosine A<sub>1</sub>-receptors

Brain neurotrophin (BDNF) is synthesized by proteolysis of proneurotrophin to form mature BDNF and the prodomain, whose regulatory activity on neuromuscular transmission is just beginning to be studied. At motor synapses, the BDNF prodomain has an inhibitory effect, stimulating GIRK potassium channels via activation of p75 receptors. The aim of this work was to study was to study the initiation and implementation of the mechanism of inhibitory action of the BDNF prodomain in mature motor synapses of the mouse diaphragm. Microelectrodes were used to record spontaneous (miniature) and multiquantal endplate potentials evoked by stimulation of motor axons (MEPP and EPP, respectively). Using selective antagonists, it was revealed that the inhibitory effect of the prodomain on synaptic transmission requires the participation of sortilin, but not TrkB receptors. Stimulation of GIRK induced by the prodomain requires the participation of synaptic metabotropic receptors, which ensure the action of βγ-subunits of Gi proteins on GIRK. Using selective inhibitors, it was found that M2 cholinergic receptors and P2Y13 purinoceptors negatively regulate presynaptic L-type calcium channels, but these metabotropic receptors are not functionally related to the action of the BDNF prodomain. It turned out that the inhibition of quantal release of acetylcholine in motor synapses caused by BDNF prodomain requires the activity of the adenosine A1-receptors only. In addition, when pannexin 1 was pharmacologically blocked by probenecid, the BDNF prodomain lost its inhibitory effect on neuromuscular transmission. Thus, BDNF prodomain-induced inhibition of quantal neurotransmitter release in mouse motor synapses requires the participation of sortilin and endogenous activation of adenosine A1-receptors, which requires the functioning of pannexins 1, which most likely provide an additional source of synaptic ATP to the vesicular one.

Seasonal variation of NGF in seminal plasma and expression of NGF and its cognate receptors NTRK1 and p75NTR in the sex organs of rams

Nerve growth factor (NGF) has long been known as the main ovulation-inducing factor in induced ovulation species, however, recent studies suggested the NGF role also in those with spontaneous ovulation. The first aim of this study was to evaluate the presence and gene expression of NGF and its cognate receptors, high-affinity neurotrophic tyrosine kinase 1 receptor (NTRK1) and low-affinity p75 nerve growth factor receptor (p75NTR), in the ram genital tract. Moreover, the annual trend of NGF seminal plasma values was investigated to evaluate the possible relationship between the NGF production variations and the ram reproductive seasonality. The presence and expression of the NGF/receptors system was evaluated in the testis, epididymis, vas deferens ampullae, seminal vesicles, prostate, and bulbourethral glands through immunohistochemistry and real-time PCR (qPCR), respectively. Genital tract samples were collected from 5 adult rams, regularly slaughtered at a local abattoir. Semen was collected during the whole year weekly, from 5 different adult rams, reared in a breeding facility, with an artificial vagina. NGF seminal plasma values were assessed through the ELISA method. NGF, NTRK1 and p75NTR immunoreactivity was detected in all male organs examined. NGF-positive immunostaining was observed in the spermatozoa of the germinal epithelium, in the epididymis and the cells of the secretory epithelium of annexed glands, NTRK1 receptor showed a localization pattern like that of NGF, whereas p75NTR immunopositivity was localized in the nerve fibers and ganglia. NGF gene transcript was highest (p < 0.01) in the seminal vesicles and lowest (p < 0.01) in the testis than in the other tissues. NTRK1 gene transcript was highest (p < 0.01) in the seminal vesicles and lowest (p < 0.05) in all the other tissues examined. Gene expression of p75NTR was highest (p < 0.01) in the seminal vesicles and lowest (p < 0.01) in the testis and bulbourethral glands. NGF seminal plasma concentration was greater from January to May (p < 0.01) than in the other months. This study highlighted that the NGF system was expressed in the tissues of all the different genital tracts examined, confirming the role of NGF in ram reproduction. Sheep are short-day breeders, with an anestrus that corresponds to the highest seminal plasma NGF levels, thus suggesting the intriguing idea that this factor could participate in an inhibitory mechanism of male reproductive activity, activated during the female anestrus.

The potential role of the p75 receptor in schizophrenia: neuroimmunomodulation and making life or death decisions

The nerve growth factor receptor, also referred to as tumour necrosis factor II and the p75 neurotrophin receptor (p75), serves pleiotropic functions in both the peripheral and central nervous system, involving modulation of immune responses, cell survival and cell death signalling in response to multiple ligands including cytokines such as TNFα, as well as proneurotrophins and mature neurotrophins. Whilst in vitro and in vivo studies have characterised various responses of the p75 receptor in isolated conditions, it remains unclear whether the p75 receptor serves to provide neuroprotection or contributes to neurotoxicity in neuroinflammatory and neurotrophin-deficit conditions, such as those presenting in schizophrenia. The purpose of this mini-review is to characterise the potential signalling mechanisms of the p75 receptor respective to neuropathological changes prevailing in schizophrenia to ultimately propose how specific functions of the receptor may underlie altered levels of p75 in specific cell types. On the basis of this evaluation, this mini-review aims to promote avenues for future research in utilising the therapeutic potential of ligands for the p75 receptor in psychiatric disorders, whereby heightened inflammation and reductions in trophic signalling mechanisms coalesce in the brain, potentially resulting in tissue damage.

Periarticular Proprioception: Analyzing the Three-Dimensional Structure of Corpuscular Mechanosensors in the Dorsal Part of the Scapholunate Ligament

Introduction: Sensory nerve endings transmit mechanical stimuli into afferent neural signals and form the basis of proprioception, giving rise to the self-perception of dynamic stability of joints. We aimed to analyze the three-dimensional structure of periarticular corpuscular sensory nerve endings in a carpal ligament to enhance our understanding of their microstructure. Methods: Two dorsal parts of the scapholunate ligament were excised from two human cadaveric wrist specimens. Consecutive cryosections were stained with immunofluorescence markers protein S100B, neurotrophin receptor p75, protein gene product 9.5 (PGP 9.5), and 4′,6-diamidino-2-phenylindole. Three-dimensional images of sensory nerve endings were obtained using confocal laser scanning microscopy, and subsequent analysis was performed using Imaris software. Results: Ruffini endings were characterized by a PGP 9.5-positive central axon, with a median diameter of 4.63 μm and a median of 25 cells. The p75-positive capsule had a range in thickness of 0.94 μm and 15.5 μm, consisting of single to three layers of lamellar cells. Ruffini endings were significantly smaller in volume than Pacini corpuscles or Golgi-like endings. The latter contained a median of three intracorpuscular structures. Ruffini endings and Golgi-like endings presented a similar structural composition of their capsule and subscapular space. The central axon of Pacini corpuscles was surrounded by S100-positive cells forming the inner core which was significantly smaller than the outer core, which was immunoreactive for p75 and PGP 9.5. Conclusion: This study reports new data regarding the intricate outer and intracorpuscular three-dimensional morphology of periarticular sensory nerve endings, including the volume, number of cells, and structural composition. These results may form a basis to differ between normal and pathological morphological changes in periarticular sensory nerve endings in future studies.

Dynamics of myelin deficits in the 5xFAD mouse model for Alzheimer's disease and the protective role of BDNF.

Recent findings highlight myelin breakdown as a decisive early event in Alzheimer's Disease (AD) acting as aggravating factor of its progression. However, it is still unclear whether myelin loss is attributed to increased oligodendrocyte vulnerability, reduced repairing capacity or toxic stimuli. In the present study, we sought to clarify the starting point of myelin disruption accompanied with Oligodendrocyte Progenitor Cell (OPC) elimination in the brain of the 5xFAD mouse model of AD at 6 months of age in Dentate Gyrus of the hippocampus in relation to neurotrophin system. Prominent inflammation presence was detected since the age of 6 months playing a key role in myelin disturbance and AD progression. Expression analysis of neurotrophin receptors in OPCs was performed to identify new targets that could increase myelination in health and disease. OPCs in both control and 5xFAD mice express TrkB, TrkC and p75 receptors but not TrkA. Brain-derived neurotrophic factor (BDNF) that binds to TrkB receptor is well-known about its pro-myelination effect, promoting oligodendrocytes proliferation and differentiation, so we focused our investigation on its effects in OPCs under neurodegenerative conditions. Our in vitro results showed that BDNF rescues OPCs from death and promotes their proliferation and differentiation in presence of the toxic Amyloid-β 1-42. Collectively, our results indicate that BDNF possess an additional neuroprotective role through its actions on oligodendrocytic component and its use could be proposed as a drug-based myelin-enhancing strategy, complementary to amyloid and tau centered therapies in AD.

Anisotropic microtopography surface of chitosan scaffold regulating skin precursor-derived Schwann cells towards repair phenotype promotes neural regeneration.

For repairing peripheral nerve and spinal cord defects, biomaterial scaffold-based cell-therapy was emerged as an effective strategy, requiring the positive response of seed cells to biomaterial substrate and environment signals. Previous work highlighted that the imposed surface properties of scaffold could provide important guidance cues to adhered cells for polarization. However, the insufficiency of native Schwann cells and unclear cellular response mechanisms remained to be addressed. Given that, this study aimed to illuminate the micropatterned chitosan-film action on the rat skin precursor-derived Schwann cells (SKP-SCs). Chitosan-film with different ridge/groove size was fabricated and applied for the SKP-SCs induction. Results indicated that SKP-SCs cultured on 30 μm size microgroove surface showed better oriented alignment phenotype. Induced SKP-SCs presented similar genic phenotype as repair Schwann cells, increasing expression of c-Jun, neural cell adhesion molecule, and neurotrophic receptor p75. Moreover, SKP-SC-secretome was subjected to cytokine array GS67 assay, data indicated the regulation of paracrine phenotype, a panel of cytokines was verified up-regulated at secreted level and gene expression level in induced SKP-SCs. These up-regulated cytokines exhibit a series of promotive neural regeneration functions, including cell survival, cell migration, cell proliferation, angiogenesis, axon growth, and cellular organization etc. through bioinformatics analysis. Furthermore, the effectively polarized SKP-SCs-sourced secretome, promoted the proliferation and migration capacity of the primarily cultured native rat Schwann cells, and augmented neurites growth of the cultured motoneurons, as well as boosted axonal regrowth of the axotomy-injured motoneurons. Taken together, SKP-SCs obtained pro-neuroregeneration phenotype in adaptive response to the anisotropic topography surface of chitosan-film, displayed the oriented parallel growth, the transition towards repair Schwann cell genic phenotype, and the enhanced paracrine effect on neural regeneration. This study provided novel insights into the potency of anisotropic microtopography surface to Schwann-like cells phenotype regulation, that facilitating to provide promising engineered cell-scaffold in neural injury therapies.

Seasonal expressions of nerve growth factor (NGF), and its receptor TrkA and p75 in the scent glands of muskrats (Ondatra zibethicus).

NGF, also known as nerve growth factor, is crucial for the survival and differentiation of the nervous system, in addition to being involved in a number of non-neuronal systems. The aim of this work was to investigate the immunolocalization and expression patterns of NGF, its receptor, tyrosine kinase receptor A (TrkA), and p75 in the scent glands of muskrats (Ondatra zibethicus) throughout the breeding and non-breeding seasons. The scent gland mass showed considerable seasonal variations, with higher values during the breeding season and comparatively lower levels during the non-breeding season. While no immunostaining was observed in the interstitial cells, NGF, TrkA, and p75 were immunolocalized in the scent glandular cells and epithelial cells during both breeding and non-breeding seasons. NGF, TrkA, and p75 protein and mRNA expression levels were higher in the scent glands during breeding season compared to the non-breeding season. Circulating levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone (T), and T in the scent gland were all significantly higher throughout the breeding season. The relative levels of the hormones in the plasma and the scent glands as well as NGF, TrkA, and p75 were positively associated with each other. Additionally, transcriptome analysis of the scent glands revealed that differentially expressed genes may be linked to steroid biosynthesis, the estrogen signaling pathway, and neurotransmitter transmembrane transporter function. These results suggest a potential role for NGF, TrkA, and p75 in controlling seasonal variations in the muskrats' scent gland functioning.

Cytotoxic effects of nerve growth factor and its combinations with chemotherapeutic drugs on anaplastoc astrocytoma, glioblastoma and medubloblastoma cells &lt;i&gt;in vitro&lt;/i&gt;

BACKGROUND: Currently, the effectiveness of the treatment of malignant tumors using surgical resection, radiotherapy and chemotherapy is insufficient. Therefore, new research is needed to find alternative molecules with antitumor effects. It is known that nerve growth factor (NGF) inhibits invasion, migration, and angiogenesis of tumor cells. Studying the effects of NGF on brain tumors, as well as its combinations with chemotherapy drugs used in medicine, may contribute to the development of new treatment regimens for malignant neoplasms in the central nervous system. AIM: The purpose of this study is an exploration the molecular and cellular mechanisms of anticancer effects of individual and combined preparations of NGF and chemotherapeutic drugs on brain tumor cells (gliomas C6, U251, anaplastic astrocytoma, glioblastoma and medulloblastoma). MATERIALS AND METHODS: The study was performed on rat glioma C6, human U251 glioma cell lines, as well as on primary cells of anaplastic astrocytoma (n = 9), glioblastoma (n = 9) and medulloblastoma (n = 38) patients. The cytotoxicity of chemotherapeutic drugs, NGF and their combinations against tumor cells was assessed using the MTT assay. The expression of TrkA and p75 receptors on anaplastic astrocytoma, glioblastoma and medulloblastoma cells was assessed by immunofluorescence analysis using anti-TrkA and anti-p75 monoclonal antibodies. RESULTS: Nerve growth factor exhibits in vitro cytotoxic activity that exceeds the activity of chemotherapy drugs towards rat glioma C6, human U251, anaplastic astrocytoma (AA), glioblastoma (GBM) and medulloblastoma cells. The cytotoxic activity of NGF in combination with chemotherapy drugs is significantly higher than the activity of the individual NGF drug against medulloblastoma cells, while against anaplastic astrocytoma cells it is comparable to the indicators of the isolated action of NGF, and lower for glioblastoma cells. The effectiveness of the cytotoxic effect of the combinations NGF + cisplatin and NGF + temozolomide (TMZ) on AA and GBM cells correlates with both the expression of TrkA, p75 receptors, and their coexpression, indicating that expression indicators can be considered as markers of tumor cell sensitivity to NGF. CONCLUSIONS: The data obtained allow us to consider NGF as a potential anticancer drug for the treatment of brain tumors. Thus, NGF can act as a potential anticancer drug for the development of new therapeutic regimens for brain tumors.

Neuroprotective potentials of Lead phytochemicals against Alzheimer's disease with focus on oxidative stress-mediated signaling pathways: Pharmacokinetic challenges, target specificity, clinical trials and future perspectives

BackgroundAlzheimer's diseases (AD) and dementia are among the highly prevalent neurological disorders characterized by deposition of beta amyloid (Aβ) plaques, dense deposits of highly phosphorylated tau proteins, insufficiency of acetylcholine (ACh) and imbalance in glutamatergic system. Patients typically experience cognitive, behavioral alterations and are unable to perform their routine activities. Evidence also suggests that inflammatory processes including excessive microglia activation, high expression of inflammatory cytokines and release of free radicals. Thus, targeting inflammatory pathways beside other targets might be the key factors to control- disease symptoms and progression. PurposeThis review is aimed to highlight the mechanisms and pathways involved in the neuroprotective potentials of lead phytochemicals. Further to provide updates regarding challenges associated with their use and their progress into clinical trials as potential lead compounds. MethodsMost recent scientific literature on pre-clinical and clinical data published in quality journals especially on the lead phytochemicals including curcumin, catechins, quercetin, resveratrol, genistein and apigenin was collected using SciFinder, PubMed, Google Scholar, Web of Science, JSTOR, EBSCO, Scopus and other related web sources. ResultsLiterature review indicated that the drug discovery against AD is insufficient and only few drugs are clinically approved which have limited efficacy. Among the therapeutic options, natural products have got tremendous attraction owing to their molecular diversity, their safety and efficacy. Research suggest that natural products can delay the disease onset, reduce its progression and regenerate the damage via their anti-amyloid, anti-inflammatory and antioxidant potentials. These agents regulate the pathways involved in the release of neurotrophins which are implicated in neuronal survival and function. Highly potential lead phytochemicals including curcumin, catechins, quercetin, resveratrol, genistein and apigenin regulate neuroprotective signaling pathways implicated in neurotrophins-mediated activation of tropomyosin receptor kinase (Trk) and p75 neurotrophins receptor (p75NTR) family receptors. ConclusionsPhytochemicals especially phenolic compounds were identified as highly potential molecules which ameliorate oxidative stress induced neurodegeneration, reduce Aβ load and inhibit vital enzymes. Yet their clinical efficacy and bioavailability are the major challenges which need further interventions for more effective therapeutic outcomes.

Urinary levels of neurotrophic factors (NGF and BDNF) in patients with detrusor overactivity

Overactive bladder refers to a group of urinary symptoms involving urinary urgency accompanied by pollakiuria or day time and nocturnal enuresis. Urodynamic testing is the gold standard for diagnosing the most frequent form of overactive bladder that is detrusor overactivity. Neurotrophins (nerve growth factor – NGF, brain-derived neurotrophic factor – BDNF, neurotrophin 3 – NT-3, and neurotrophin 4 – NT-4) are proteins secreted by the nervous system, found in many tissues, including bladder cells. They are bound by two types of receptors: low- and high-affinity receptors, two of which, i.e. tropomyosin receptor kinase A (TrkA) and p75 receptor, are located in the epithelial cells of the urinary bladder. The detrusor muscle was shown to secrete NGF in response to stretching of the urinary bladder. In addition, numerous studies have shown an increase in the urinary levels of NGF and BDNF in patients with overactive bladder and their decrease after the introduction of anticholinergic therapy. Therefore, the assessment of urinary levels of neurotrophins NGF and BDNF seems to be useful as a potential biomarker of detrusor overactivity. Unfortunately, the sensitivity of these parameters in the diagnosis of detrusor overactivity is low due to the possible overlapping of other conditions, especially bladder pain syndrome, which affects mainly adults. Additionally, previous studies have been conducted in small groups of patients, therefore studies in a larger population are needed. Confirming the usefulness of these biomarkers in the future opens the opportunity to replace the urodynamic test with the analysis of urinary markers, which would significantly simplify diagnosis and increase patient’s comfort.

#125 : The Role of BDNF Receptors in the Incidence of Endometrioma Tissue Invasion Onto the Chorioallantoic Membrane

Background and Aims: Previous studies have explored the role of neurotrophins and their receptors, especially in forming deep endometriosis, endometriosis tissue invasion, and its effects on tissue proliferation. However, these studies do not include research on the pathogenesis of endometriomas. We tried to model the invasion of endometrioma tissue to find out more about its pathogenesis by using the chorioallantoic membrane (CAM) as the host. Immunohistochemistry (IHC) to detect neurotrophin BDNF and its receptors, namely TrkB and P75, are employed and linked between their expression and the process of invasion and proliferation. Method: The endometriotic tissue samples were collected from women (n=27) who underwent hysteroscopy/laparoscopy at Dr. Sardjito Central Hospital. Peritoneal endometriosis (PE) lession, endometrioma (CC), and eutopic endometrium (EN) was analyzed with 15 tissue samples in each group. Samples were placed in a tube containing transport medium and transplanted into CAM of fertile chicken eggs for five days. Transplanted tissue was harvested, and histological preparations were made using the paraffin method. IHC staining was performed on p75, Ki67, TrkB, and BDNF staining. Invasion analysis and IHC evaluation were performed with a semi-quantitative method. Data were analyzed using IBMⓇ SPSS Statistics version 25.0. Statistical significance was accepted at P &lt; 0.05. Results: Normal Endometrium expressed the highest expression of BDNF than peritoneal endometriosis and endometrioma (0.36± 0.38, 0.16± 0.13, 0.07± 0.07, P=0.007). The P75 expression correlated positively with Ki67 expression in PE and CC samples (P=0.012; P=0.008). Conclusion: The p75 receptor may have a role in endometriosis tissue proliferation, but this receptor does not directly influence tissue invasion into CAM. While proliferation in endometriomas positively correlates with invasion into CAM, it is not correlated with peritoneal endometriosis.

A study to determine systemic anti-inflammatory mediators in chronic obstructive pulmonary disorder

Background: Chronic obstructive pulmonary disorder (COPD) is a prevalent and debilitating respiratory condition characterized by chronic inflammation within the airways and lung tissues. By elucidating the specific mediators involved and their potential therapeutic implications, this research seeks to contribute to a better understanding of the inflammatory mechanisms underlying COPD and explore novel avenues for managing the disease. Aims and Objectives: The objective of study is to determine systemic anti-inflammatory mediators in COPD and its correlation with disease severity. Materials and Methods: The study analyzed systemic levels of several anti-inflammatory mediators, namely, soluble interleukin 1 receptor II (sIL-1RII), soluble tumor necrosis factor receptor p55 (sTNF-R55), and sTNF-R75, as well as C-reactive protein (CRP) and lipopolysaccharide binding protein (LBP), in 55 patients with stable COPD (median forced expiratory volume in 1 s [FEV1] of 34% predicted, ranging from 15% to 78%) and compared them with 23 control subjects. In addition, changes in these mediators were studied in 13 COPD patients (median FEV1 of 34% predicted, ranging from 19% to 51%) during the first 7 days of hospitalization for an exacerbation of the disease. Results: The results revealed that patients with stable COPD showed evidence of a systemic inflammatory process, characterized by an elevated leukocyte count, increased levels of CRP and LBP, and moderate increases in both sTNF-Rs. However, the sIL-1RII levels did not differ significantly between patients and controls. During the treatment of disease exacerbations, systemic levels of CRP (at day 3) and LBP (at day 7) significantly decreased compared to day 1, while sIL-1RII levels increased. Conclusion: Based on these findings, it is suggested that there is an imbalance in systemic levels of pro- and anti-inflammatory mediators in patients with stable COPD. The observed increase in the anti-inflammatory mediator sIL-1RII during treatment of exacerbations may play a role in the clinical improvement observed in these patients.

Genetic and Pharmacological Modulation of P75 Neurotrophin Receptor Attenuate Brain Damage After Ischemic Stroke in Mice.

The precursor nerve growth factor (ProNGF) and its receptor p75 neurotrophin receptor (p75NTR) are upregulated in several brain diseases, including ischemic stroke. The activation of p75NTR is associated with neuronal apoptosis and inflammation. Thus, we hypothesized that p75NTR modulation attenuates brain damage and improves functional outcomes after ischemic stroke. Two sets of experiments were performed. (1) Adult wild-type (WT) C57BL/6J mice were subjected to intraluminal suture-middle cerebral artery occlusion (MCAO) to induce cerebral ischemia. Pharmacological inhibitor of p75NTR, LM11A-31 (50mg/kg), or normal saline was administered intraperitoneally (IP)1h post-MCAO, and animals survived for 24h. (2) Adult p75NTR heterozygous knockout (p75NTR+/-) and WT were subjected to photothrombotic (pMCAO) to induce ischemic stroke, and the animals survived for 72h. The sensory-motor function of animals was measured using Catwalk XT. The brain samples were collected to assess infarction volume, edema, hemorrhagic transformation, neuroinflammation, and signaling pathway at 24 and 72h after the stroke. The findings described that pharmacological inhibition and genetic knocking down of p75NTR reduce infarction size, edema, and hemorrhagic transformation following ischemic stroke. Additionally, p75NTR modulation significantly decreased several anti-apoptosis markers and improved sensory motor function compared to the WT mice following ischemic stroke. Our observations exhibit that the involvement of p75NTR in ischemic stroke and modulation of p75NTR could improve the outcome of ischemic stroke by increasing cell survival and enhancing motor performance. LM11A-31 has the potential to be a promising therapeutic agent for ischemic stroke. However, more evidence is needed to illuminate the efficacy of LM11A-31 in ischemic stroke.

Schwann Cells Reprogram Into Repair Phenotype Instead of Dedifferentiating to Immature Phenotype in in Vitro Culture

Introduction: In vitro cultured Schwann cell has been suggested to adopt a phenotype of undifferentiated immature Schwann cells found in vivo during development. However, recent studies indicate that Schwann cells undergo cellular reprogramming into the phenotype of repair Schwann cells instead of reverting to an immature phenotype after peripheral nerve injury. The study hypothesized that in in vitro culture, Schwann cells assume the repair phenotype instead of de-differentiating to immature Schwann cells, similar to in vivo nerve injury response. Therefore, this study aimed to characterize the phenotype of cultured Schwann cells by examining the expression of classic Schwann markers and transcription factors c-Jun and Krox-20. Methods: Schwann cells, isolated from Wistar rat sciatic nerve, were grown in a standard Schwann cell growth medium for seven days. Then, cultured Schwann cells were analyzed using immunofluorescence analysis for classic Schwann cell markers (neurotrophin receptor p75 (p75NTR) and myelin basic protein (MBP)) and the expression profile of transcription factor c-Jun and Krox-20. Results: Immunofluorescence analysis revealed that cultured Schwann cells expressed a significantly high level of repair phenotype biomarkers (p75NTR and c-Jun) compared to the level of myelinating phenotype biomarkers (MBP and Krox-20). Conclusion: Schwann cells reprogram into repair Schwann cells instead of de-differentiating to immature Schwann cells in vitro.

Thymosin Beta 4 Protects Hippocampal Neuronal Cells against PrP (106-126) via Neurotrophic Factor Signaling.

Prion protein peptide (PrP) has demonstrated neurotoxicity in brain cells, resulting in the progression of prion diseases with spongiform degenerative, amyloidogenic, and aggregative properties. Thymosin beta 4 (Tβ4) plays a role in the nervous system and may be related to motility, axonal enlargement, differentiation, neurite outgrowth, and proliferation. However, no studies about the effects of Tβ4 on prion disease have been performed yet. In the present study, we investigated the protective effect of Tβ4 against synthetic PrP (106-126) and considered possible mechanisms. Hippocampal neuronal HT22 cells were treated with Tβ4 and PrP (106-126) for 24 h. Tβ4 significantly reversed cell viability and reactive oxidative species (ROS) affected by PrP (106-126). Apoptotic proteins induced by PrP (106-126) were reduced by Tβ4. Interestingly, a balance of neurotrophic factors (nerve growth factor and brain-derived neurotrophic factor) and receptors (nerve growth factor receptor p75, tropomyosin related kinase A and B) were competitively maintained by Tβ4 through receptors reacting to PrP (106-126). Our results demonstrate that Tβ4 protects neuronal cells against PrP (106-126) neurotoxicity via the interaction of neurotrophic factors/receptors.

Neural cell adhesion molecule 1 is a cellular target engaged plasma biomarker in demyelinating Charcot-Marie-Tooth disease.

Elevated plasma concentrations of neural cell adhesion molecule 1 (NCAM1) and p75 neurotrophin receptor (p75) in patients with peripheral neuropathy have been reported. This study aimed to determine the specificity of plasma concentration elevation of either NCAM1 or p75 in a subtype of Charcot-Marie-Tooth disease (CMT) and its correlation with pathologic nerve status and disease severity. Blood samples were collected from 138 patients with inherited peripheral neuropathy and 51 healthy controls. Disease severity was measured using Charcot-Marie-Tooth Neuropathy Score version 2 (CMTNSv2), and plasma concentrations of NCAM1 and p75 were analyzed by enzyme-linked immunosorbent assay. Eight sural nerves from CMT patients were examined to determine the relation of histopathology and plasma NCAM1 levels. Plasma concentration of NCAM1, but not p75, was specifically increased in demyelinating subtypes of CMT (median=7100 pg/mL, p <0.001), including CMT1A, but not in axonal subtype (5964 pg/mL, p >0.05), compared to the control (3859 pg/mL). CMT1A patients with mild or moderate severity (CMTNSv2 < 20) showed higher levels of plasma NCAM1 than healthy controls. Immunofluorescent NCAM1 staining for the sural nerves of CMT patients showed that NCAM1-positive onion bulb cells and possible demyelinating Schwann cells might be associated with the specific increase of plasma NCAM1 in demyelinating CMT. The plasma NCAM1 levels in demyelinating CMT might be a surrogate biomarker reflecting pathological Schwann cell status and disease progression.

BDNF/TrkB signaling endosomes in axons coordinate CREB/mTOR activation and protein synthesis in the cell body to induce dendritic growth in cortical neurons.

Brain-derived neurotrophic factor (BDNF) and its receptors tropomyosin kinase receptor B (TrkB) and the p75 neurotrophin receptor (p75) are the primary regulators of dendritic growth in the CNS. After being bound by BDNF, TrkB and p75 are endocytosed into endosomes and continue signaling within the cell soma, dendrites, and axons. We studied the functional role of BDNF axonal signaling in cortical neurons derived from different transgenic mice using compartmentalized cultures in microfluidic devices. We found that axonal BDNF increased dendritic growth from the neuronal cell body in a cAMP response element-binding protein (CREB)-dependent manner. These effects were dependent on axonal TrkB but not p75 activity. Dynein-dependent BDNF-TrkB-containing endosome transport was required for long-distance induction of dendritic growth. Axonal signaling endosomes increased CREB and mTOR kinase activity in the cell body, and this increase in the activity of both proteins was required for general protein translation and the expression of Arc, a plasticity-associated gene, indicating a role for BDNF-TrkB axonal signaling endosomes in coordinating the transcription and translation of genes whose products contribute to learning and memory regulation.