Role of RhoA-ROCK signaling in Parkinson's disease

Exploring the Role of RhoA/ROCK Signaling in Pain: A Narrative Review

Despite significant progress in understanding the mechanisms of pain and developing therapeutic agents, pain remains a challenging and unresolved clinical issue. The Ras homolog gene family member A (RhoA), a member of the small guanosine triphosphate hydrolases (GTPases) of the Ras homolog family, is involved in transmitting signals that regulate various cellular processes. RhoA exerts its effects through a range of downstream effectors, with Rho-associated kinase (ROCK) being the most extensively studied. Emerging evidence suggests that the RhoA/ROCK signaling pathway plays a crucial role in pain transmission and sensitization. Our work indicates that targeting the RhoA/ROCK signaling pathway may offer a promising therapeutic avenue for alleviating pain.

Drug Repositioning and Repurposing for Disease-Modifying Effects in Parkinson's Disease

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder and is characterized by progressive dopaminergic and nondopaminergic neuronal loss and the presence of Lewy bodies, which are primarily composed of aggregated α-synuclein. Despite advancements in symptomatic therapies, such as dopamine replacement and deep brain stimulation, no disease-modifying therapies (DMTs) have been identified to slow or arrest neurodegeneration in patients with PD. Challenges in DMT development include disease heterogeneity, the absence of reliable biomarkers, and the multifaceted pathophysiology of PD, encompassing neuroinflammation, mitochondrial dysfunction, lysosomal impairment, and oxidative stress. Drug repositioning and repurposing strategies using existing drugs for new therapeutic applications offer promising approaches to accelerate the development of DMTs for PD. These strategies minimize time, cost, and risk by using compounds with established safety profiles. Prominent candidates include glucagon-like peptide-1 receptor agonists, dipeptidyl peptidase-4 inhibitors, ambroxol, calcium channel blockers, statins, iron-chelating agents, c-Abl inhibitors, and memantine. Although preclinical and early clinical studies have demonstrated encouraging results, numerous phase III trials have yielded unfavorable outcomes, elucidating the complexity of PD pathophysiology and the need for innovative trial designs. This review evaluates the potential of prioritized repurposed drugs for PD, focusing on their mechanisms, preclinical evidence, and clinical trial outcomes, and highlights the ongoing challenges and opportunities in this field.

S1PR3 in hippocampal neurons improves synaptic plasticity and decreases depressive behavior via downregulation of RhoA/ROCK1

The study investigates how Sphingosine-1-phosphate receptor 3 (S1PR3) and the Chronic Unpredictable Mild Stress (CUMS) affects depression-like behaviors. The S1P/S1PR3 signaling pathway is known to play a role in mood regulation, but it is not yet fully understood how it is connected to depression. This study looks to further explore this topic. To investigate the effect of CUMS on S1PR3 expression in hippocampus neurons and the synaptic plasticity, we observed animals' behavior with Sucrose Preference Test (SPT), Forced Swim Test (FST) and Open Field Test (OFT). Combining molecular and histological analysis, we investigated the S1PR3 expression, the change in synapse density, and synaptic structure change in the hippocampus. The CUMS caused a significant decrease in the S1PR3 expression, the density of the synaptic spine and synaptic ultrastructure change in mice. On the other hand, over-expression of S1PR3 by adeno-associated virus (AAV) in hippocampal neurons alleviated the depressive-like behaviors and synaptic deficits observed in stress-susceptible animals. Furthermore, the depressive-like phenotype and synaptic impairments were normalized by the expression of RhoA, implicating the RhoA/ROCK1 pathway in S1PR3 actions. Collectively, our findings provide strong evidence that S1PR3 plays a key role in hippocampal synaptic plasticity and depression and that modulation of S1PR3/RhoA/ROCK1 signaling may offer a novel therapeutic strategy for MDD. This study not only underscores the therapeutic potential of S1PR3 but also provides novel insights into the molecular mechanisms underlying depression.

Fasudil inhibits α-synuclein aggregation through ROCK-inhibition-mediated mechanisms

ROCK inhibitors such as fasudil protected against dopaminergic degeneration and other neurodegenerative processes in several experimental models through inhibition of neuroinflammation and activation of survival signaling pathways, and clinical trials have been initiated. More recently, fasudil has been suggested to inhibit α-synuclein aggregation. However, this is controversial, particularly if it is a consequence of direct binding of the fasudil molecule to α-synuclein. We studied the mechanisms involved in the effects of fasudil on α-synuclein aggregation using the α-synuclein-T/V5-synphilin-1 model. Molecule-molecule interactions were studied using real time quaking inducing conversion (RT-QuiC). Fasudil decreased the number of cells with inclusions and the size of inclusions in dopaminergic neurons and glial cells, and inhibited α-synuclein aggregation and microglial endocytosis of aggregates. These changes were not due to changes in α-synuclein protein expression or phosphorylation and were related to ROCK inhibition rather than direct interaction with α-synuclein, as confirmed with a second ROCK inhibitor (Y27632) and ROCK gene silencing. We observed that ROCK inhibition downregulates several factors that are known to promote α-synuclein aggregation such as NADPH-oxidase-derived oxidative stress, intracellular calcium increase, and α-synuclein endocytosis, and promotes autophagy. The present results support that fasudil is a useful drug against Parkinson's disease progression. In addition to other reported neuroprotective properties, fasudil inhibits α-synuclein aggregation and microglial endocytosis of aggregates, which enhances the microglial inflammatory response. The effects of fasudil are mostly related to ROCK inhibition, which we have shown using two structurally different ROCK inhibitors and knockdown data, and further supported by using RT-QuiC.

The role of RhoA-ROCK signaling in benign prostatic hyperplasia: a review

Benign prostatic hyperplasia (BPH) is a common urological disease in middle-aged and elderly men. The main pathological mechanisms of BPH include static factors that increase prostate volume and dynamic factors that increase prostate tension. The RhoA/ROCK signaling pathway is a classical pathway that regulates cell contraction, migration, and growth. In this review, we summarize the potential role of RhoA/ROCK signaling in the development of BPH. The RhoA/ROCK signaling pathway can enhance the contraction of prostate smooth muscle through the Ca2+ sensitization pathway and increase passive tension in the prostate through tissue fibrosis. Additionally, RhoA/ROCK signaling promotes cell proliferation by regulating cell division and may influence apoptosis by affecting the actin cytoskeleton. Furthermore, risk factors, such as inflammation, metabolic syndrome, and hormonal changes, can upregulate RhoA/ROCK signaling, which in turn promotes these risk factors, eventually leading to the development of BPH. Given the role of RhoA/ROCK signaling in regulating multiple pathogenic factors of BPH, this pathway represents a promising molecular target for BPH treatment and warrants further study.

New insights on the regulators and inhibitors of RhoA-ROCK signalling in Parkinson's disease

A multifaceted and widely prevalent neurodegenerative disease, Parkinson's disease (PD) is typified by the loss of dopaminergic neurons in the midbrain. The discovery of novel treatment(s) that can reverse or halt the course of the disease progression along with identifying the most reliable biomarker(s) in PD remains the crucial concern. RhoA in its active state has been demonstrated to interact with three distinct domains located in the central coiled-coil region of ROCK. RhoA appears to activate effectors most frequently by breaking the intramolecular autoinhibitory connections, which releases functional domains from the effector protein. Additionally, RhoA is highly expressed in the nervous system and it acts as a central molecule for its several downstream effector proteins in multiple signalling pathways both in neurons and glial cells. Mitochondrial dysfunction, vesicle transport malfunction and aggregation of α-Synuclein, a presynaptic neuronal protein genetically and neuropathologically associated with PD. While the RhoA-ROCK signalling pathway appears to have a significant role in PD symptoms, suggesting it could be a promising target for therapeutic interventions. Thus, this review article addresses the potential involvement of the RhoA-ROCK signalling system in the pathophysiology of neurodegenerative illnesses, with an emphasis on its biology and function. We also provide an overview of the state of research on RhoA regulation and its downstream biological activities, focusing on the role of RhoA signalling in neurodegenerative illnesses and the potential benefits of RhoA inhibition as a treatment for neurodegeneration.

RhoA/ROCK2 signaling pathway regulates Mn-induced alterations in tight junction proteins leading to cognitive dysfunction in mice

Elevated manganese (Mn) exposure has been implicated in a broad spectrum of neurological disorders, including motor dysfunction and cognitive deficits. Previous studies have demonstrated that Mn induces neurotoxicity by disrupting the integrity of the blood-brain barrier (BBB), a critical regulator in maintaining central nervous system homeostasis and a contributing factor in the pathogenesis of numerous neurological disorders. However, the precise molecular mechanisms underlying Mn-induced BBB disruption and its role in facilitating neurotoxicity remain incompletely understood. The primary objectives of this study were to elucidate the mechanisms underlying the relationship between Mn exposure and BBB tight junction proteins (TJPs), and to further investigate potential neuroprotective strategies for mitigating Mn-induced cognitive impairments. In this investigation, we developed Mn exposure models utilizing both murine subjects and cell culture systems to elucidate the mechanisms underlying TJPs involvement and to assess the potential neuroprotective effects of gastrodin (GAS), a bioactive compound extracted from traditional Chinese medicine. Our findings revealed a significant reduction in TJPs expression, both in vivo and in vitro, in Mn-induced BBB disruption. The overexpression of Occludin (OCLN), a crucial component of TJPs, mitigated Mn-induced BBB damage. GAS administration effectively attenuated Mn-induced disruption of the BBB, enhanced the expression of TJPs, and mitigated Mn-induced cognitive dysfunctions, potentially through the modulation of the RhoA/ROCK2 signaling pathway. This research sought to advance our understanding of the molecular pathways involved in Mn-mediated BBB disruption and to identify novel therapeutic approaches for mitigating the deleterious effects of Mn exposure on cognitive function.

Protective effects and mechanism of quercetin from Rhododendron dauricum against cerebral ischemia-reperfusion injury

METHODS

This study seeks to identify the bioactive compounds within Rhododendron dauricum and explore potential mechanisms for treating cerebral I/R injury through a comprehensive analysis employing network pharmacology, complemented by experimental validation.

RESULTS

The core targets associated with quercetin in the treatment of cerebral I/R injury are TNF-α, IL-6, IL-1β, and AKT1. Notably, we propose for the first time that its mode of action primarily involves the inhibition of the TNF-α/RhoA/ROCK2 pathway.

CONCLUSION

Our findings reveal that quercetin emerges as a pivotal bioactive component of Rhododendron dauricum in the context of cerebral I/R injury treatment.

Evaluating the Role of Lin-11, Isl-1, and Mec-3 Kinases in Dopaminergic Neurodegeneration in a Subacute 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine Model of Parkinson's Disease

The malfunctioning of microtubules is highly correlated with neurodegenerative disorders such as Parkinson's disease (PD), although whether it is a cause or an effect of neurodegeneration is yet unknown. Lin-11, Isl-1, and Mec-3 kinases (LIMKs), being one of the important kinases, regulate the neuronal cytoskeleton by controlling the phosphorylation of the cofilin/actin-depolymerizing factor. Recently, we showed that upregulation of phosphorylated LIMK1 (p-LIMK1) affects the microtubule dynamics in a central nervous system traumatic injury. The goal of this study is to correlate the expression of LIMK1 with dopaminergic neuron death in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine model of PD, one of the well-established subacute models of PD, where the neurotoxin acts via inhibition of mitochondrial complex I of the electron transport chain. Herein, we found that LIMK1 expression was increased and correlated to dopaminergic neuronal death. Finally, we demonstrated that the treatment with LIMK inhibitor BMS-5 significantly reversed the neurodegeneration, along with an upregulation of the dynamic tubulins, indicating the relevance of LIMKs and microtubule dynamics in neurodegeneration. Therefore, targeting the microtubules, an integral part of the neuronal cytoskeleton and neurite formation, can be a promising strategy to combat degeneration of dopaminergic neurons.

Role of Rho-associated kinases and their inhibitor fasudil in neurodegenerative diseases

Neurodegenerative diseases (NDDs) are prevalent in the elderly. The pathogenesis of NDDs is complex, and currently, there is no cure available. With the increase in aging population, over 20 million people are affected by common NDDs alone (Alzheimer's disease and Parkinson's disease). Therefore, NDDs have profound negative impacts on patients, their families, and society, making them a major global health concern. Rho-associated kinases (ROCKs) belong to the serine/threonine protein kinases family, which modulate diverse cellular processes (e.g., apoptosis). ROCKs may elevate the risk of various NDDs (including Huntington's disease, Parkinson's disease, and Alzheimer's disease) by disrupting synaptic plasticity and promoting inflammatory responses. Therefore, ROCK inhibitors have been regarded as ideal therapies for NDDs in recent years. Fasudil, one of the classic ROCK inhibitor, is a potential drug for treating NDDs, as it repairs nerve damage and promotes axonal regeneration. Thus, the current review summarizes the relationship between ROCKs and NDDs and the mechanism by which fasudil inhibits ROCKs to provide new ideas for the treatment of NDDs.

Investigating causality and shared genetic architecture between body mass index and cognitive function: a genome-wide cross-trait analysis and bi-directional Mendelian randomization study

Background and objectives

Observational studies have established a connection between body mass index (BMI) and an increased risk of cognitive decline. However, a comprehensive investigation into the causal relationships between BMI and cognitive function across diverse age groups, as well as the genetic underpinnings of this relationship, has been notably lacking. This study aims to investigate causality and the shared genetic underpinnings of between BMI and cognitive function by conducting a thorough genome-wide analysis, thereby provide valuable insights for developing personalized intervention strategies to promote cognitive health.

Methods

Genetic associations between BMI and cognitive function were thoroughly investigated through covariate genetic analysis and chained imbalance score regression, utilizing data from genome-wide association studies (GWAS). Bi-directional Mendelian Randomization (MR) was employed to uncover associations and potential functional genes were further scrutinized through Cross-trait meta-analysis and Summary-data-based MR (SMR). Subsequently, a detailed examination of the expression profiles of the identified risk SNPs in tissues and cells was conducted.

Results

The study found a significant negative correlation between BMI and cognitive function (β = -0.16, P = 1.76E-05), suggesting a causal linkage where higher BMI values were predictive of cognitive impairment. We identified 5 genetic loci (rs6809216, rs7187776, rs11713193, rs13096480, and rs13107325) between BMI and cognitive function by cross-trait meta-analysis and 5 gene-tissue pairs were identified by SMR analysis. Moreover, two novel risk genes TUFM and MST1R were shared by both cross-trait analysis and SMR analysis, which had not been observed in previous studies. Furthermore, significant enrichment of single nucleotide polymorphisms (SNPs) at tissue- and cell-specific levels was identified for both BMI and cognitive function, predominantly within the brain.

Conclusion

This study uncovers a causal relationship between BMI and cognitive function, with the discovery of TUFM and MST1R as shared genetic factors associated with both conditions. This novel finding offers new insights into the development of preventative strategies for cognitive decline in obese individuals, and further enhances our understanding of the underlying pathophysiology of these conditions. Furthermore, these findings could serve as a guide for the development of innovative therapeutic approaches to address cognitive decline in obese individuals.

How Protein Depletion Balances Thrombosis and Bleeding Risk in the Context of Platelet's Activatory and Negative Signaling

Platelets are small cell fragments that play a crucial role in hemostasis, requiring fast response times and fine signaling pathway regulation. For this regulation, platelets require a balance between two pathway types: the activatory and negative signaling pathways. Activatory signaling mediators are positive responses that enhance stimuli initiated by a receptor in the platelet membrane. Negative signaling regulates and controls the responses downstream of the same receptors to roll back or even avoid spontaneous thrombotic events. Several blood-related pathologies can be observed when these processes are unregulated, such as massive bleeding in activatory signaling inhibition or thrombotic events for negative signaling inhibition. The study of each protein and metabolite in isolation does not help to understand the role of the protein or how it can be contrasted; however, understanding the balance between active and negative signaling could help develop effective therapies to prevent thrombotic events and bleeding disorders.

Rapid iPSC inclusionopathy models shed light on formation, consequence, and molecular subtype of α-synuclein inclusions

The heterogeneity of protein-rich inclusions and its significance in neurodegeneration is poorly understood. Standard patient-derived iPSC models develop inclusions neither reproducibly nor in a reasonable time frame. Here, we developed screenable iPSC "inclusionopathy" models utilizing piggyBac or targeted transgenes to rapidly induce CNS cells that express aggregation-prone proteins at brain-like levels. Inclusions and their effects on cell survival were trackable at single-inclusion resolution. Exemplar cortical neuron α-synuclein inclusionopathy models were engineered through transgenic expression of α-synuclein mutant forms or exogenous seeding with fibrils. We identified multiple inclusion classes, including neuroprotective p62-positive inclusions versus dynamic and neurotoxic lipid-rich inclusions, both identified in patient brains. Fusion events between these inclusion subtypes altered neuronal survival. Proteome-scale α-synuclein genetic- and physical-interaction screens pinpointed candidate RNA-processing and actin-cytoskeleton-modulator proteins like RhoA whose sequestration into inclusions could enhance toxicity. These tractable CNS models should prove useful in functional genomic analysis and drug development for proteinopathies.

miR-101a-3p/ROCK2 axis regulates neuronal injury in Parkinson's disease models

BACKGROUND

Parkinson's disease (PD) is a neurodegenerative disease characterized by the loss of dopaminergic neurons in substantia nigra pars compacta (SNpc). This study focuses on deciphering the role of microRNA (miR)-101a-3p in the neuronal injury of PD and its regulatory mechanism.

METHODS

We constructed a mouse model of PD by intraperitoneal injection of 1-methyl 4-phenyl 1, 2, 3, 6-tetrahydropyridine hydrochloride (MPTP), and used 1-methyl-4-phenylpyridinium (MPP+) to treat Neuro-2a cells to construct an in-vitro PD model. Neurological dysfunction in mice was evaluated by swimming test and traction test. qRT-PCR was utilized to examine miR-101a-3p expression and ROCK2 expression in mouse brain tissues and Neuro-2a cells. Western blot was conducted to detect the expression of α-synuclein protein and ROCK2 in mouse brain tissues and Neuro-2a cells. The targeting relationship between miR-101a-3p and ROCK2 was determined by dual-luciferase reporter gene assay. The apoptosis of neuro-2a cells was assessed by flow cytometry.

RESULTS

Low miR-101a-3p expression and high ROCK2 expression were found in the brain tissues of PD mice and MPP+-treated Neuro-2a cells; PD mice showed decreased neurological disorders, and apoptosis of Neuro-2a cells was increased after MPP+ treatment, both of which were accompanied by increased accumulation of α-synuclein protein. After miR-101a-3p was overexpressed, the neurological function of PD mice was improved, and the apoptosis of Neuro-2a cells induced by MPP+ was alleviated, and the accumulation of α-synuclein protein was reduced; ROCK2 overexpression counteracted the protective effect of miR-101a-3p. Additionally, ROCK2 was identified as the direct target of miR-101a-3p.

CONCLUSION

MiR-101a-3p can reduce neuronal apoptosis and neurological deficit in PD mice by inhibiting ROCK2 expression, suggesting that miR-101a-3p is a promising therapeutic target for PD.

S1PR2 participates in intestinal injury in severe acute pancreatitis by regulating macrophage pyroptosis

Background

Severe acute pancreatitis (SAP) is an inflammatory disorder affecting the gastrointestinal system. Intestinal injury plays an important role in the treatment of severe acute pancreatitis. In this study, we mainly investigated the role of S1PR2 in regulating macrophage pyroptosis in the intestinal injury of severe acute pancreatitis.

Methods

The SAP model was constructed using cerulein and lipopolysaccharide, and the expression of S1PR2 was inhibited by JTE-013 to detect the degree of pancreatitis and intestinal tissue damage in mice. Meanwhile, the level of pyroptosis-related protein was detected by western blot, the level of related mRNA was detected by PCR, and the level of serum inflammatory factors was detected by ELISA. In vitro experiments, LPS+ATP was used to construct the pyroptosis model of THP-1. After knockdown and overexpression of S1PR2, the pyroptosis proteins level was detected by western blot, the related mRNA level was detected by PCR, and the level of cell supernatant inflammatory factors were detected by ELISA. A rescue experiment was used to verify the sufficient necessity of the RhoA/ROCK pathway in S1PR2-induced pyroptosis. Meanwhile, THP-1 and FHC were co-cultured to verify that cytokines released by THP-1 after damage could regulate FHC damage.

Results

Our results demonstrated that JTE-013 effectively attenuated intestinal injury and inflammation in mice with SAP. Furthermore, we observed a significant reduction in the expression of pyroptosis-related proteins within the intestinal tissue of SAP mice upon treatment with JTE-013. We confirmed the involvement of S1PR2 in THP-1 cell pyroptosis in vitro. Specifically, activation of S1PR2 triggered pyroptosis in THP-1 cells through the RhoA/ROCK signaling pathway. Moreover, it was observed that inflammatory factors released during THP-1 cell pyroptosis exerted an impact on cohesin expression in FHC cells.

Conclusion

The involvement of S1PR2 in SAP-induced intestinal mucosal injury may be attributed to its regulation of macrophage pyroptosis.

Midbrain organoids for Parkinson's disease (PD) - A powerful tool to understand the disease pathogenesis

Brain Organiods (BOs) are a promising technique for researching disease progression in the human brain. These organoids, which are produced from human induced pluripotent stem cells (HiPSCs), can construct themselves into structured frameworks. In the context of Parkinson's disease (PD), recent advancements have been made in the development of Midbrain organoids (MBOs) models that consider key pathophysiological mechanisms such as alpha-synuclein (α-Syn), Lewy bodies, dopamine loss, and microglia activation. However, there are limitations to the current use of BOs in disease modelling and drug discovery, such as the lack of vascularization, long-term differentiation, and absence of glial cells. To address these limitations, researchers have proposed the use of spinning bioreactors to improve oxygen and nutrient perfusion. Modelling PD utilising modern experimental in vitro models is a valuable tool for studying disease mechanisms and elucidating previously unknown features of PD. In this paper, we exclusively review the unique methods available for cultivating MBOs using a pumping system that mimics the circulatory system. This mechanism may aid in delivering the required amount of oxygen and nutrients to all areas of the organoids, preventing cell death, and allowing for long-term culture and using co-culturing techniques for developing glial cell in BOs. Furthermore, we emphasise some of the significant discoveries about the BOs and the potential challenges of using BOs will be discussed.

Insights into Calpain Activation and Rho-ROCK Signaling in Parkinson's Disease and Aging

Parkinson's disease (PD), a progressive neurodegenerative disease, has no cure, and current therapies are not effective at halting disease progression. The disease affects mid-brain dopaminergic neurons and, subsequently, the spinal cord, contributing to many debilitating symptoms associated with PD. The GTP-binding protein, Rho, plays a significant role in the cellular pathology of PD. The downstream effector of Rho, Rho-associated kinase (ROCK), plays multiple functions, including microglial activation and induction of inflammatory responses. Activated microglia have been implicated in the pathology of many neurodegenerative diseases, including PD, that initiate inflammatory responses, leading to neuron death. Calpain expression and activity is increased following glial activation, which triggers the Rho-ROCK pathway and induces inflammatory T cell activation and migration as well as mediates toxic α-synuclein (α-syn) aggregation and neuron death, indicating a pivotal role for calpain in the inflammatory and degenerative processes in PD. Increased calpain activity and Rho-ROCK activation may represent a new mechanism for increased oxidative damage in aging. This review will summarize calpain activation and the role of the Rho-ROCK pathway in oxidative stress and α-syn aggregation, their influence on the neurodegenerative process in PD and aging, and possible strategies and research directions for therapeutic intervention.

The Molecular Pathway of p75 Neurotrophin Receptor (p75NTR) in Parkinson's Disease: The Way of New Inroads

Parkinson's disease (PD) is a chronic and progressive neurodegenerative disease of the brain. PD is characterized by motor and non-motor symptoms. The p75 neurotrophin receptor (p75NTR) is a functional receptor for different growth factors including pro-brain derived neurotrophic factor (pro-BDNF), neurotrophin 3 (NT-3), and neurotrophin 4 (NT-4). Consequently, this review aimed to illustrate the detrimental and beneficial role of p75NTR in PD. Diverse studies showed that p75NTR and its downstream signaling are intricate in the pathogenesis of PD. Nevertheless, pro-apoptotic and pro-survival pathways mediated by p75NTR in PD were not fully clarified. Of note, p75NTR plays a critical role in the regulation of dopaminergic neuronal survival and apoptosis in the CNS. Particularly, p75NTR can induce selective apoptosis of dopaminergic neurons and progression of PD. In addition, p75NTR signaling inhibits the expression of transcription factors which are essential for the survival of dopaminergic neurons. Also, p75NTR expression is connected with the severity of dopaminergic neuronal injury. These verdicts implicate p75NTR signaling in the pathogenesis of PD, though the underlying mechanistic pathways remain not elucidated. Collectively, the p75NTR signaling pathway induces a double-sword effect either detrimental or beneficial depending on the ligands and status of PD neuropathology. Therefore, p75NTR signaling seems to be protective via phosphoinositide 3-kinase (PI3K)/AKT and Bcl-2 and harmful via activation of JNK, caspase 3, nuclear factor kappa B (NF-κB), and RhoA pathways.

Plausible Role of Mitochondrial DNA Copy Number in Neurodegeneration-a Need for Therapeutic Approach in Parkinson's Disease (PD)

Parkinson's disease (PD) is an advancing age-associated progressive brain disorder which has various diverse factors, among them mitochondrial dysfunction involves in dopaminergic (DA) degeneration. Aging causes a rise in mitochondrial abnormalities which leads to structural and functional modifications in neuronal activity and cell death in PD. This ends in deterioration of mitochondrial function, mitochondrial alterations, mitochondrial DNA copy number (mtDNA CN) and oxidative phosphorylation (OXPHOS) capacity. mtDNA levels or mtDNA CN in PD have reported that mtDNA depletion would be a predisposing factor in PD pathogenesis. To maintain the mtDNA levels, therapeutic approaches have been focused on mitochondrial biogenesis in PD. The depletion of mtDNA levels in PD can be influenced by autophagic dysregulation, apoptosis, neuroinflammation, oxidative stress, sirtuins, and calcium homeostasis. The current review describes the regulation of mtDNA levels and discusses the plausible molecular pathways in mtDNA CN depletion in PD pathogenesis. We conclude by suggesting further research on mtDNA depletion which might show a promising effect in predicting and diagnosing PD.

Role of Telomeres and Telomerase in Parkinson's Disease-A New Theranostics?

Parkinson's disease (PD) is a complex condition that is significantly influenced by oxidative stress and inflammation. It is also suggested that telomere shortening (TS) is regulated by oxidative stress which leads to various diseases including age-related neurodegenerative diseases like PD. Thus, it is anticipated that PD would result in TS of peripheral blood mononuclear cells (PBMCs). Telomeres protect the ends of eukaryotic chromosomes preserving them against fusion and destruction. The TS is a normal process because DNA polymerase is unable to replicate the linear ends of the DNA due to end replication complications and telomerase activity in various cell types counteracts this process. PD is usually observed in the aged population and progresses over time therefore, disparities among telomere length in PBMCs of PD patients are recorded and it is still a question whether it has any useful role. Here, the likelihood of telomere attrition in PD and its implications concerning microglia activation, ageing, oxidative stress, and the significance of telomerase activators are addressed. Also, the possibility of telomeres and telomerase as a diagnostic and therapeutic biomarker in PD is discussed.

Modeling methamphetamine use disorder and relapse in animals: short- and long-term epigenetic, transcriptional., and biochemical consequences in the rat brain

Methamphetamine use disorder (MUD) is a neuropsychiatric disorder characterized by binge drug taking episodes, intervals of abstinence, and relapses to drug use even during treatment. MUD has been modeled in rodents and investigators are attempting to identify its molecular bases. Preclinical experiments have shown that different schedules of methamphetamine self-administration can cause diverse transcriptional changes in the dorsal striatum of Sprague-Dawley rats. In the present review, we present data on differentially expressed genes (DEGs) identified in the rat striatum following methamphetamine intake. These include genes involved in transcription regulation, potassium channel function, and neuroinflammation. We then use the striatal data to discuss the potential significance of the molecular changes induced by methamphetamine by reviewing concordant or discordant data from the literature. This review identified potential molecular targets for pharmacological interventions. Nevertheless, there is a need for more research on methamphetamine-induced transcriptional consequences in various brain regions. These data should provide a more detailed neuroanatomical map of methamphetamine-induced changes and should better inform therapeutic interventions against MUD.

Proteomic analysis of exosomes derived from human mature milk and colostrum of mothers with term, late preterm, or very preterm delivery

The growth and development of the human brain is a long and complex process that requires a precise sequence of genetic and molecular events. This begins in the third week of gestation with the differentiation of neural progenitor cells and extends at least until late adolescence, possibly for life. One of the defects of this development is that we know very little about the signals that modulate this sequence of events. The first 3 years of life, during breastfeeding, is one of the critical periods in brain development. In these first years of life, it is believed that neurodevelopmental problems may be the molecular causes of mental disorders. Therefore, we herein propose a new hypothesis, according to which the chemical signals that could modulate this entire complex sequence of events appear in this early period, and the molecular level study of human breast milk and colostrum of mothers who give birth to children in different gestation periods could give us information on proteins influencing this process. In this work, we collected milk and colostrum samples (term, late preterm and moderate/very preterm) and exosomes were isolated. The samples of exosomes and complete milk from each fraction were analyzed by LC-ESI-MS/MS. In this work, we describe proteins in the different fractions of mature milk and colostrum of mothers with term, late preterm, or very preterm delivery, which could be involved in the regulation of the nervous system by their functions. We describe how they differ in different types of milk, paving the way for the investigation of possible new neuroregulatory pathways as possible candidates to modulate the nervous system.

The Involvement of Neuroinflammation in the Onset and Progression of Parkinson's Disease

Parkinson's disease is a neurodegenerative disease exhibiting the fastest growth in incidence in recent years. As with most neurodegenerative diseases, the pathophysiology is incompletely elucidated, but compelling evidence implicates inflammation, both in the central nervous system and in the periphery, in the initiation and progression of the disease, although it is not yet clear what triggers this inflammatory response and where it begins. Gut dysbiosis seems to be a likely candidate for the initiation of the systemic inflammation. The therapies in current use provide only symptomatic relief, but do not interfere with the disease progression. Nonetheless, animal models have shown promising results with therapies that target various vicious neuroinflammatory cascades. Translating these therapeutic strategies into clinical trials is still in its infancy, and a series of issues, such as the exact timing, identifying biomarkers able to identify Parkinson's disease in early and pre-symptomatic stages, or the proper indications of genetic testing in the population at large, will need to be settled in future guidelines.

Type 2 Diabetes (T2DM) and Parkinson's Disease (PD): a Mechanistic Approach

Growing evidence suggest that there is a connection between Parkinson's disease (PD) and insulin dysregulation in the brain, whilst the connection between PD and type 2 diabetes mellitus (T2DM) is still up for debate. Insulin is widely recognised to play a crucial role in neuronal survival and brain function; any changes in insulin metabolism and signalling in the central nervous system (CNS) can lead to the development of various brain disorders. There is accumulating evidence linking T2DM to PD and other neurodegenerative diseases. In fact, they have a lot in common patho-physiologically, including insulin dysregulation, oxidative stress resulting in mitochondrial dysfunction, microglial activation, and inflammation. As a result, initial research should focus on the role of insulin and its molecular mechanism in order to develop therapeutic outcomes. In this current review, we will look into the link between T2DM and PD, the function of insulin in the brain, and studies related to impact of insulin in causing T2DM and PD. Further, we have also highlighted the role of various insulin signalling pathway in both T2DM and PD. We have also suggested that T2DM-targeting pharmacological strategies as potential therapeutic approach for individuals with cognitive impairment, and we have demonstrated the effectiveness of T2DM-prescribed drugs through current PD treatment trials. In conclusion, this investigation would fill a research gap in T2DM-associated Parkinson's disease (PD) with a potential therapy option.

Fluoride exposure disrupts the cytoskeletal arrangement and ATP synthesis of HT-22 cell by activating the RhoA/ROCK signaling pathway

BACKGROUND

Fluoride, an environmental contaminant, is ubiquitously present in air, water, and soil. It usually enters the body through drinking water and may cause structural and functional disorders in the central nervous system in humans and animals. Fluoride exposure affects cytoskeleton and neural function, but the mechanism is not clear.

METHODS

The specific neurotoxic mechanism of fluoride was explored in HT-22 cells. Cellular proliferation and toxicity detection were investigated by CCK-8, CCK-F, and cytotoxicity detection kits. The development morphology of HT-22 cells was observed under a light microscope. Cell membrane permeability and neurotransmitter content were determined using lactate dehydrogenase (LDH) and glutamate content determination kits, respectively. The ultrastructural changes were detected by transmission electron microscopy, and actin homeostasis was observed by laser confocal microscopy. ATP enzyme and ATP activity were determined using the ATP content kit and ultramicro-total ATP enzyme content kit, respectively. The expression levels of GLUT1 and 3 were assessed by Western Blot assays and qRT-PCR.

RESULTS

Our results showed that fluoride reduced the proliferation and survival rates of HT-22 cells. Cytomorphology showed that dendritic spines became shorter, cellular bodies became rounder, and adhesion decreased gradually after fluoride exposure. LDH results showed that fluoride exposure increased the membrane permeability of HT-22 cells. Transmission electron microscopy results showed that fluoride caused cells to swell, microvilli content decreased, cellular membrane integrity was damaged, chromatin was sparse, mitochondria ridge gap became wide, and microfilament and microtubule density decreased. Western Blot and qRT-PCR analyses showed that RhoA/ROCK/LIMK/Cofilin signaling pathway was activated by fluoride. F-actin/G-actin fluorescence intensity ratio remarkably increased in 0.125 and 0.5 mM NaF, and the mRNA expression of MAP2 was significantly decreased. Further studies showed that GLUT3 significantly increased in all fluoride groups, while GLUT1 decreased (p < 0.05). ATP contents remarkably increased, and ATP enzyme activity substantially decreased after NaF treatment with the control.

CONCLUSION

Fluoride activates the RhoA/ROCK/LIMK/Cofilin signaling pathway, impairs the ultrastructure, and depresses the connection of synapses in HT-22 cells. Moreover, fluoride exposure affects the expression of glucose transporters (GLUT1 and 3) and ATP synthesis. Sum up fluoride exposure disrupts actin homeostasis, ultimately affecting structure, and function in HT-22 cells. These findings support our previous hypothesis and provide a new perspective on the neurotoxic mechanism of fluorosis.

Promising biomarkers and therapeutic targets for the management of Parkinson's disease: recent advancements and contemporary research

Parkinson's disease (PD) is one of the progressive neurological diseases which affect around 10 million population worldwide. The clinical manifestation of motor symptoms in PD patients appears later when most dopaminergic neurons have degenerated. Thus, for better management of PD, the development of accurate biomarkers for the early prognosis of PD is imperative. The present work will discuss the potential biomarkers from various attributes covering biochemical, microRNA, and neuroimaging aspects (α-synuclein, DJ-1, UCH-L1, β-glucocerebrosidase, BDNF, etc.) for diagnosis, recent development in PD management, and major limitations with current and conventional anti-Parkinson therapy. This manuscript summarizes potential biomarkers and therapeutic targets, based on available preclinical and clinical evidence, for better management of PD.

Exploring the mechanism of Chaihujia Longgu Muli decoction in the treatment of epilepsy in rats based on the RhoA/ROCK signaling pathway

BACKGROUND

The Chinese herbal formula Chaihujia Longgu Muli Decoction (CD) has a good antiepileptic effect, but its mechanisms remain unclear. Therefore, in this study we explored the molecular mechanisms of CD against epilepsy.

METHODS

Twelve-day-old SD rats were randomly divided into a normal group, model group, valproic acid group, and CD high, medium, and low groups. Except for the normal group, the other groups were given an intraperitoneal injection of pentylenetetrazol (PTZ) to establish epilepsy models, and the Racine score was applied for model judgment. After 14 consecutive days of dosing, the Morris water maze test was performed. Then, hippocampal Nissl staining and immunofluorescence staining were performed, and synaptic ultrastructure was observed by transmission electron microscopy (TEM). RhoA/ROCK signaling pathway proteins were detected.

RESULTS

In PTZ model rats, the passing times were reduced, and the escape latency was prolonged in the Morris water maze test. Nissl staining showed that some hippocampal neurons swelled and ruptured, Nissl bodies in the cytoplasm were significantly reduced, and neurons were lost. Immunofluorescence detection revealed that the expression of PSD95 and SYP was significantly reduced. Electron microscopy results revealed that the number of synapses in hippocampal neurons was significantly reduced and the postsynaptic membrane length was significantly reduced. Western blot analysis showed that the RhoA/ROCK signaling pathway was activated, while SYP, SPD95, and PTEN expression was significantly decreased. After treatment with CD, neurobehavioral abnormalities and neuronal damage caused by epileptic seizures were improved.

CONCLUSION

CD exerted an antiepileptic effect by inhibiting the activation of the RhoA/ROCK signaling pathway.

miRNA in Parkinson's disease: From pathogenesis to theranostic approaches

Parkinson's disease (PD) is an age associated neurological disorder which is specified by cardinal motor symptoms such as tremor, stiffness, bradykinesia, postural instability, and non-motor symptoms. Dopaminergic neurons degradation in substantia nigra region and aggregation of αSyn are the classic signs of molecular defects noticed in PD pathogenesis. The discovery of microRNAs (miRNA) predicted to have a pivotal part in various processes regarding regularizing the cellular functions. Studies on dysregulation of miRNA in PD pathogenesis has recently gained the concern where our review unravels the role of miRNA expression in PD and its necessity in clinical validation for therapeutic development in PD. Here, we discussed how miRNA associated with ageing process in PD through molecular mechanistic approach of miRNAs on sirtuins, tumor necrosis factor-alpha and interleukin-6, dopamine loss, oxidative stress and autophagic dysregulation. Further we have also conferred the expression of miRNAs affected by SNCA gene expression, neuronal differentiation and its therapeutic potential with PD. In conclusion, we suggest more rigorous studies should be conducted on understanding the mechanisms and functions of miRNA in PD which will eventually lead to discovery of novel and promising therapeutics for PD.

Biochemical Pathways of Cellular Mechanosensing/Mechanotransduction and Their Role in Neurodegenerative Diseases Pathogenesis

In this review, we shed light on recent advances regarding the characterization of biochemical pathways of cellular mechanosensing and mechanotransduction with particular attention to their role in neurodegenerative disease pathogenesis. While the mechanistic components of these pathways are mostly uncovered today, the crosstalk between mechanical forces and soluble intracellular signaling is still not fully elucidated. Here, we recapitulate the general concepts of mechanobiology and the mechanisms that govern the mechanosensing and mechanotransduction processes, and we examine the crosstalk between mechanical stimuli and intracellular biochemical response, highlighting their effect on cellular organelles' homeostasis and dysfunction. In particular, we discuss the current knowledge about the translation of mechanosignaling into biochemical signaling, focusing on those diseases that encompass metabolic accumulation of mutant proteins and have as primary characteristics the formation of pathological intracellular aggregates, such as Alzheimer's Disease, Huntington's Disease, Amyotrophic Lateral Sclerosis and Parkinson's Disease. Overall, recent findings elucidate how mechanosensing and mechanotransduction pathways may be crucial to understand the pathogenic mechanisms underlying neurodegenerative diseases and emphasize the importance of these pathways for identifying potential therapeutic targets.

Neurotoxicity of pesticides - A link to neurodegeneration

Parkinson's disease (PD) is a neurodegenerative disorder which mainly targets motor symptoms such as tremor, rigidity, bradykinesia and postural instability. The physiological changes occur due to dopamine depletion in basal ganglia region of the brain. PD aetiology is not yet elucidated clearly but genetic and environmental factors play a prominent role in disease occurrence. Despite of various environmental factors, pesticides exposure has been convicted as major candidate in PD pathogenesis. Among various pesticides 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) has been widely investigated in PD following with paraquat (PQ), maneb (MB), organochlorines (OC) and rotenone. Effect of these pesticides has been suggested to be involved in oxidative stress, alterations in dopamine transporters, mitochondrial dysfunction, α-synuclein (αSyn) fibrillation, and neuroinflammation in PD. The present review discusses the influence of pesticides in neurodegeneration and its related epidemiological studies conducted in PD. Furthermore, we have deliberated the common pesticides involved in PD and its associated genetic alterations and the probable mechanism of them behind PD pathogenesis. Hence, we conclude that pesticides play a prominent role in PD pathogenesis and advance research is needed to investigate the alterations in genetic and mechanistic aspects of PD.

Role of heavy metals (copper (Cu), arsenic (As), cadmium (Cd), iron (Fe) and lithium (Li)) induced neurotoxicity

Parkinson's disease (PD) is a neurodegenerative condition characterized by the dopamine (DA) neuronal loss in the substantia nigra. PD impairs motor controls symptoms such as tremor, rigidity, bradykinesia and postural imbalance gradually along with non-motor problems such as olfactory dysfunction, constipation, sleeping disorder. Though surplus of factors and mechanisms have been recognized, the precise PD etiopathogenesis is not yet implied. Reports suggest that various environmental factors play a crucial role in the causality of the PD cases. Epidemiological studies have reported that heavy metals has a role in causing defects in substantia nigra region of brain in PD. Though the reason is unknown, exposure to heavy metals is reported to be an underlying factor in PD development. Metals are classified as either essential or non-essential, and they have a role in physiological processes such protein modification, electron transport, oxygen transport, redox reactions, and cell adhesion. Excessive metal levels cause oxidative stress, protein misfolding, mitochondrial malfunction, autophagy dysregulation, and apoptosis, among other things. In this review, we check out the link between heavy metals like copper (Cu), arsenic (As), cadmium (Cd), iron (Fe), and lithium (Li) in neurodegeneration, and how it impacts the pathological conditions of PD. In conclusion, increase or decrease in heavy metals involve in regulation of neuronal functions that have an impact on neurodegeneration process. Through this review, we suggest that more research is needed in this stream to bring more novel approaches for either disease modelling or therapeutics.

Influence of heavy metals in Parkinson's disease: an overview

Parkinson's disease (PD) is an ageing disorder with deterioration of dopamine neurons which leads to motor complications like tremor, stiffness, slow movement and postural disturbances. In PD, both genetics as well as environmental factors both play a major role in causing the pathogenesis. Though there are surfeit of risk factors involved in PD occurrence, till now there is lack of an exact causative agent as a risk for PD with confirmative findings. The role of heavy metals reported to be a significant factor in PD pathogenesis. Heavy metal functions in cell maintenance but growing pieces of evidences reported to cause dyshomeostasis with increased PD rate. Metals disturb the molecular processes and results in oxidative stress, DNA damage, mitochondrial dysfunction, and apoptosis. The present review elucidates the role of cobalt, nickel, mercury, chromium, thallium metals in α-synuclein aggregation and its involvement in blood brain barrier flux. Also, the review explains the plausible role of aforementioned metals with a mechanistic approach and therapeutic recommendations in PD.

Protection against Hypoxia-Reoxygenation Injury of Hippocampal Neurons by H2S via Promoting Phosphorylation of ROCK2 at Tyr722 in Rat Model

The RhoA-ROCK signaling pathway is associated with the protective effects of hydrogen sulfide (H₂S) against cerebral ischemia. H₂S protects rat hippocampal neurons (RHNs) against hypoxia-reoxygenation (H/R) injury by promoting phosphorylation of RhoA at Ser188. However, effect of H₂S on the phosphorylation of ROCK₂-related sites is unclear. The present study was designed to investigate whether H₂S can play a role in the phosphorylation of ROCK₂ at Tyr722, and explore whether this role mediates the protective effect of H/R injury in RHNs. Prokaryotic recombinant plasmids ROCK₂^wild-pGEX-6P-1 and ROCK₂^Y722F-pGEX-6P-1 were constructed and transfected into E. coli in vitro, and the expressed protein, GST-ROCK₂^wild and GST-ROCK₂^Y722F were used for phosphorylation assay in vitro. Eukaryotic recombinant plasmids ROCK₂^Y722-pEGFP-N1 and ROCK₂^Y722F-pEGFP-N1 as well as empty plasmid were transfected into the RHNs. Western blot assay and whole-cell patch-clamp technique were used to detect phosphorylation of ROCK₂ at Tyr722 and BK_Ca channel current in the RHNs, respectively. Cell viability, leakages of intracellular enzymes lactate dehydrogenase (LDH), and nerve-specific enolase (NSE) were measured. The H/R injury was indicated by decrease of cell viability and leakages of intracellular LDH and NSE. The results of Western blot have shown that NaHS, a H₂S donor, significantly promoted phosphorylation of GST-ROCK₂^wild at Tyr722, while no phosphorylation of GST-ROCK₂^Y722F was detected. The phosphorylation of ROCK₂^wild promoted by NaHS was also observed in RHNs. NaHS induced more potent effects on protection against H/R injury, phosphorylation of ROCK₂ at Tyr722, inhibition of ROCK₂ activity, as well as increase of the BK_Ca current in the ROCK₂^Y722-pEGFP-N1-transfected RHNs. Our results revealed that H₂S protects the RHNs from H/R injury through promoting phosphorylation of ROCK₂ at Tyr722 to inhibit ROCK₂ activity and potentially by opening channel currents.

ANKFN1 plays both protumorigenic and metastatic roles in hepatocellular carcinoma

Ankyrin repeat and fibronectin type III domain containing 1 (ANKFN1) is reported to be involved in human height and developmental abnormalities, but the expression profile and molecular function of ANKFN1 in hepatocellular carcinoma (HCC) remain unknown. This study aimed to evaluate the clinical significance and biological function of ANKFN1 in HCC and investigate whether ANKFN1 can be used for differential diagnosis in HCC. Here, we showed that ANKFN1 was upregulated in 126 tumor tissues compared with adjacent nontumorous tissues in HCC patients. The upregulation of ANKFN1 in HCC was associated with cirrhosis, alpha-fetoprotein (AFP) levels and poor prognosis. Moreover, silencing ANKFN1 expression suppressed HCC cell proliferation, migration, invasion, and metastasis in vitro and subcutaneous tumorigenesis in vivo. However, ANKFN1 overexpression promoted HCC proliferation and metastasis in an orthotopic liver transplantation model and attenuated the above biological effects in HCC cells. ANKFN1 significantly affected HCC cell proliferation by inducing G1/S transition and cell apoptosis. Mechanistically, we demonstrated that ANKFN1 promoted cell proliferation, migration, and invasion via activation of the cyclin D1/Cdk4/Cdk6 pathway by stimulating the MEK1/2-ERK1/2 pathway. Moreover, ANKFN1-induced cell proliferation, migration, and invasion were partially reversed by ERK1/2 inhibitors. Taken together, our results indicate that ANKFN1 promotes HCC cell proliferation and metastasis by activating the MEK1/2-ERK1/2 signaling pathway. Our work also suggests that ANKFN1 is a potential therapeutic target for HCC.

Effects of RhoA on depression-like behavior in prenatally stressed offspring rats

Depression is a common mental disease that can lead to suicide when severe. Exposure to prenatal stress (PS) can lead to depression-like behavior in offspring, but the mechanism is unclear. RhoA (Ras homology family member A) plays an important role in stress-induced changes in synaptic plasticity, participating in the development of depression by activating the downstream effector ROCK (Rho-associated protein kinase). This study explored the influence in the expression of RhoA and downstream molecules ROCK1/2 in prenatally stressed rats, and the effect of RhoA inhibitor simvastatin on depression-like behavior induced by PS. Depression-like behavior in offspring was detected by sucrose preference test, forced swimming test, and open-field test. The mRNA and protein expression of RhoA and ROCK1/2 in the hippocampus and prefrontal cortex of offspring rats were detected by qRT-PCR and western blotting, respectively. Our results showed that PS causes depression-like behavior in offspring rats, associated with elevated expression of RhoA, ROCK1/2 in the hippocampus and prefrontal cortex. After administration of simvastatin to PS rats, the expression of RhoA and ROCK2 was significantly reduced, alleviating depression-like behavior. Our study demonstrated that RhoA participates in the depression-like behavior in prenatally stressed offspring rats, which may be a potential target for antidepressant therapy.

Emerging Therapeutic Strategies for Parkinson’s Disease and Future Prospects: A 2021 Update

Parkinson’s disease (PD) is a neurodegenerative disorder pathologically distinguished by degeneration of dopaminergic neurons in the substantia nigra pars compacta. Muscle rigidity, tremor, and bradykinesia are all clinical motor hallmarks of PD. Several pathways have been implicated in PD etiology, including mitochondrial dysfunction, impaired protein clearance, and neuroinflammation, but how these factors interact remains incompletely understood. Although many breakthroughs in PD therapy have been accomplished, there is currently no cure for PD, only trials to alleviate the related motor symptoms. To reduce or stop the clinical progression and mobility impairment, a disease-modifying approach that can directly target the etiology rather than offering symptomatic alleviation remains a major unmet clinical need in the management of PD. In this review, we briefly introduce current treatments and pathophysiology of PD. In addition, we address the novel innovative therapeutic targets for PD therapy, including α-synuclein, autophagy, neurodegeneration, neuroinflammation, and others. Several immunomodulatory approaches and stem cell research currently in clinical trials with PD patients are also discussed. Moreover, preclinical studies and clinical trials evaluating the efficacy of novel and repurposed therapeutic agents and their pragmatic applications with encouraging outcomes are summarized. Finally, molecular biomarkers under active investigation are presented as potentially valuable tools for early PD diagnosis.

Axonal Protection by Netarsudil, a ROCK Inhibitor, Is Linked to an AMPK-Autophagy Pathway in TNF-Induced Optic Nerve Degeneration

Purpose

Netarsudil, a Rho kinase inhibitor with norepinephrine transport inhibitory effect, lowers intraocular pressure, however, its effect on axon damage remains to be elucidated. The aim of the current study was to investigate the effect of netarsudil on TNF-induced axon loss and to examine whether it affects phosphorylated-AMP-activated kinase (p-AMPK) and autophagy in the optic nerve.

Methods

Intravitreal administration of TNF or TNF with netarsudil was carried out on rats and quantification of axon number was determined. Electron microscopy determined autophagosome numbers. Localization of p-AMPK expression was examined by immunohistochemistry. The changes in p62, LC3-II, and p-AMPK levels were estimated in the optic nerve by immunoblot analysis. The effect of an AMPK activator A769662 or an AMPK inhibitor dorsomorphin on axon number was evaluated.

Results

Morphometric analysis revealed apparent protection by netarsudil against TNF-induced axon degeneration. Netarsudil increased autophagosome numbers inside axons. Netarsudil treatment significantly upregulated optic nerve LC3-II levels in both the TNF-treated eyes and the control eyes. Increased p62 protein level induced by TNF was significantly ameliorated by netarsudil. The netarsudil administration alone lessened p62 levels. Netarsudil significantly upregulated the optic nerve p-AMPK levels. A769662 exhibited obvious axonal protection against TNF-induced damage. A769662 treatment upregulated LC3-II levels and the increment of p62 level induced by TNF was significantly ameliorated by A769662. Immunohistochemical analysis revealed that p-AMPK is present in axons. Netarsudil-mediated axonal protection was significantly suppressed by dorsomorphin administration.

Conclusions

Netarsudil upregulated p-AMPK and autophagy. Netarsudil-mediated axonal protection may be associated with upregulated p-AMPK.

A six-metabolite panel as potential blood-based biomarkers for Parkinson's disease

Characterisation and diagnosis of idiopathic Parkinson's disease (iPD) is a current challenge that hampers both clinical assessment and clinical trial development with the potential inclusion of non-PD cases. Here, we used a targeted mass spectrometry approach to quantify 38 metabolites extracted from the serum of 231 individuals. This cohort is currently one of the largest metabolomic studies including iPD patients, drug-naïve iPD, healthy controls and patients with Alzheimer's disease as a disease-specific control group. We identified six metabolites (3-hydroxykynurenine, aspartate, beta-alanine, homoserine, ornithine (Orn) and tyrosine) that are significantly altered between iPD patients and control participants. A multivariate model to predict iPD from controls had an area under the curve (AUC) of 0.905, with an accuracy of 86.2%. This panel of metabolites may serve as a potential prognostic or diagnostic assay for clinical trial prescreening, or for aiding in diagnosing pathological disease in the clinic.

Electrospun meshes intrinsically promote M2 polarization of microglia under hypoxia and offer protection from hypoxia-driven cell death

In this study, we offer new insights into the contrasting effects of electrospun fiber orientation on microglial polarization under normoxia and hypoxia, and establish for the first time, the intrinsically protective roles of electrospun meshes against hypoxia-induced microglial responses. First, resting microglia were cultured under normoxia on poly(caprolactone) fibers possessing two distinctly different fiber orientations. Matrix-guided differences in cell shape/orientation and differentially expressed Rho GTPases (RhoA, Rac1, Cdc42) were well-correlated with the randomly oriented fibers inducing a pro-inflammatory phenotype and the aligned fibers sustaining a resting phenotype. Upon subsequent hypoxia induction, both sets of meshes offered protection from hypoxia-induced damage by promoting a radical phenotypic switch and beneficially altering the M2/M1 ratio to different extents. Compared to 2D hypoxic controls, meshes significantly suppressed the expression of pro-inflammatory markers (IL-6, TNF-α) and induced drastically higher expression of anti-inflammatory (IL-4, IL-10, VEGF-189) and neuroprotective (Nrf-2) markers. Consistent with this M2 polarization, the expression of Rho GTPases was significantly lower in the mesh groups under hypoxia compared to normoxic culture. Moreover, meshes-particularly with aligned fibers-promoted higher cell viability, suppressed caspase 3/8 and LC-3 expression and promoted LAMP-1 and LAMP-2 expression, which suggested the mitigation of apoptotic/autophagic cell death via a lysosomal membrane-stabilization mechanism. Notably, all protective effects under hypoxia were observed in the absence of additional soluble cues. Our results offer promise for leveraging the intrinsic therapeutic potential of electrospun meshes in degenerative diseases where microglial dysfunction, hypoxia and inflammation are implicated.

PEA prevented early BBB disruption after cerebral ischaemic/reperfusion (I/R) injury through regulation of ROCK/MLC signaling

Palmitoylethanolamide (PEA) offers a strong protection against BBB disruption and neurological deficits after cerebral ischaemic/reperfusion (I/R) injury. To date, these BBB protective effects of PEA are mainly attributed to PPARα-mediated actions. However, whether PEA protects against BBB disruption through direct regulation of cytoskeletal microfilaments remains unknown. Here, we identified PEA as a Rho-associated protein kinase (ROCK2) inhibitor (IC₅₀ = 38.4 ± 4.8 μM). In vitro data suggested that PEA reduced the activation of ROCK/MLC signaling and stress fiber formation within microvascular endothelial cells (ECs) after oxygen-glucose deprivation (OGD), and consequently attenuated early (0-4 h) EC barrier disruption. These actions of PEA could not be blocked by the PPARα antagonist GW6471. In summary, the present study described a previously unexplored role of PEA as a ROCK2 inhibitor, and propose a PPARα-independent mechanism for pharmacological effects of PEA.