Metalloproteinases: mediators of pathology and regeneration in the CNS

Convergent and divergent transcriptional reprogramming of motor and sensory neurons underlying response to peripheral nerve injury

INTRODUCTION

Motor neurons differ from sensory neurons in aspects including origins and surrounding environment. Understanding the similarities and differences in molecular response to peripheral nerve injury (PNI) and regeneration between sensory and motor neurons is crucial for developing effective drug targets for CNS regeneration. However, genome-wide comparisons of molecular changes between sensory and motor neurons following PNI remains limited.

OBJECTIVES

This study aims to investigate genome-wide convergence and divergence of injury response between sensory and motor neurons to identify novel drug targets for neural repair.

METHODS

We analyzed two large-scale RNA-seq datasets of in situ captured sensory neurons (SNs) and motoneurons (MNs) upon PNI, retinal ganglion cells and spinal cord upon CNS injury. Additionally, we integrated these with other related single-cell level datasets. Bootstrap DESeq2 and WGCNA were used to detect and explore co-expression modules of differentially expressed genes (DEGs).

RESULTS

We found that SNs and MNs exhibited similar injury states, but with a delayed response in MNs. We identified a conserved regeneration-associated module (cRAM) with 274 shared DEGs. Of which, 47% of DEGs could be changed in injured neurons supported by single-cell resolution datasets. We also identified some less-studied candidates in cRAM, including genes associated with transcription, ubiquitination (Rnf122), and neuron-immune cells cross-talk. Further in vitro experiments confirmed a novel role of Rnf122 in axon growth. Analysis of the top 10% of DEGs with a large divergence suggested that both extrinsic (e.g., immune microenvironment) and intrinsic factors (e.g., development) contributed to expression divergence between SNs and MNs following injury.

CONCLUSIONS

This comprehensive analysis revealed convergent and divergent injury response genes in SNs and MNs, providing new insights into transcriptional reprogramming of sensory and motor neurons responding to axonal injury and subsequent regeneration. It also identified some novel regeneration-associated candidates that may facilitate the development of strategies for axon regeneration.

Differences in metalloproteinases and their tissue inhibitors in the cerebrospinal fluid are associated with delirium

BACKGROUND

The aetiology of delirium is not known, but pre-existing cognitive impairment is a predisposing factor. Here we explore the associations between delirium and cerebrospinal fluid (CSF) levels of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs), proteins with important roles in both acute injury and chronic neurodegeneration.

METHODS

Using a 13-plex Discovery Assay®, we quantified CSF levels of 9 MMPs and 4 TIMPs in 280 hip fracture patients (140 with delirium), 107 cognitively unimpaired individuals, and 111 patients with Alzheimer's disease dementia. The two delirium-free control groups without acute trauma were included to unravel the effects of acute trauma (hip fracture), dementia, and delirium.

RESULTS

Here we show that delirium is associated with higher levels of MMP-2, MMP-3, MMP-10, TIMP-1, and TIMP-2; a trend suggests lower levels of TIMP-4 are also associated with delirium. Most delirium patients had pre-existing dementia and low TIMP-4 is the only marker associated with delirium in adjusted analyses. MMP-2, MMP-12, and TIMP-1 levels are clearly higher in the hip fracture patients than in both control groups and several other MMP/TIMPs are impacted by acute trauma or dementia status.

CONCLUSIONS

Several CSF MMP/TIMPs are significantly associated with delirium in hip fracture patients, but alterations in most of these MMP/TIMPs could likely be explained by acute trauma and/or pre-fracture dementia. Low levels of TIMP-4 appear to be directly associated with delirium, and the role of this marker in delirium pathophysiology should be further explored.

Revolutionizing Stroke Care: Nanotechnology-Based Brain Delivery as a Novel Paradigm for Treatment and Diagnosis

Stroke, a severe medical condition arising from abnormalities in the coagulation-fibrinolysis cycle and metabolic processes, results in brain cell impairment and injury due to blood flow obstruction within the brain. Prompt and efficient therapeutic approaches are imperative to control and preserve brain functions. Conventional stroke medications, including fibrinolytic agents, play a crucial role in facilitating reperfusion to the ischemic brain. However, their clinical efficacy is hampered by short plasma half-lives, limited brain tissue distribution attributed to the blood-brain barrier (BBB), and lack of targeted drug delivery to the ischemic region. To address these challenges, diverse nanomedicine strategies, such as vesicular systems, polymeric nanoparticles, dendrimers, exosomes, inorganic nanoparticles, and biomimetic nanoparticles, have emerged. These platforms enhance drug pharmacokinetics by facilitating targeted drug accumulation at the ischemic site. By leveraging nanocarriers, engineered drug delivery systems hold the potential to overcome challenges associated with conventional stroke medications. This comprehensive review explores the pathophysiological mechanism underlying stroke and BBB disruption in stroke. Additionally, this review investigates the utilization of nanocarriers for current therapeutic and diagnostic interventions in stroke management. By addressing these aspects, the review aims to provide insight into potential strategies for improving stroke treatment and diagnosis through a nanomedicine approach.

Prognosticating acute traumatic spinal cord injury using Neurofilament (NF), Neuron Specific Enolase (NSE), Matrix Metalloproteinases (MMPs), and S-100B as biomarkers

BACKGROUND

Spinal cord injury (SCI) can result in lifelong disability. Currently, the literature suggests that biomarkers are helpful in prognosticating SCI, but there is no specific biomarker to date. This is the first study that predicted the prognosis dynamically using biomarkers.

AIM

To elucidate the role of biomarkers in prognosticating acute traumatic SCI.

METHODS

Blood samples were obtained from 35 patients of acute traumatic SCI at presentation, immediate post-op, and at 6 weeks. At 6 months follow-up, patients were divided into two groups, i.e, improved and non-improved based on the improvement in the ASIA grade compared to presentation. A non-parametric test was used for comparing mean NSE, MMP-2, S100-B, and NF serum levels at presentation, immediate post-op, and 6 weeks post-op follow-up between the two groups.

RESULTS

There was a significant difference (p = 0.03) in the NF values at presentation between the two groups. The difference of NSE values at 6 weeks was also significant (p = 0.016) between the two groups. S-100B levels were also significantly different between both groups at presentation (p=0.016), and at the immediate post-op stage (p=0.007). MMP-2 levels neither displayed any specific trend nor any significant difference between the two groups.

CONCLUSION

Higher NF values at presentation, and higher S-100B levels at presentation and immediate post-operative period correlated with poor outcome. Also, increased NSE values after surgery are indicative of no improvement. These levels can be used at various stages to predict the prognosis. However, further studies are required on this topic extensively to know the exact cut-off values of these markers to predict the prognosis accurately.

CLINICAL TRIALS REGISTRY NUMBER

REF/2020/01/030616.

An analysis of neutrophil-to-lymphocyte ratios and monocyte-to-lymphocyte ratios with six-month prognosis after cerebral contusions

Background and purpose

Neutrophil-to-lymphocyte ratio (NLR) and monocyte-to-lymphocyte ratio (MLR) have been identified as potential prognostic markers in various conditions, including cancer, cardiovascular disease, and stroke. This study aims to investigate the dynamic changes of NLR and MLR following cerebral contusion and their associations with six-month outcomes.

Methods

Retrospective data were collected from January 2016 to April 2020, including patients diagnosed with cerebral contusion and discharged from two teaching-oriented tertiary hospitals in Southern China. Patient demographics, clinical manifestations, laboratory test results (neutrophil, monocyte, and lymphocyte counts) obtained at admission, 24 hours, and one week after cerebral contusion, as well as outcomes, were analyzed. An unfavorable outcome was defined as a Glasgow Outcome Score (GOS) of 0-3 at six months. Logistic regression analysis was performed to identify independent predictors of prognosis, while receiver characteristic curve analysis was used to determine the optimal cutoff values for NLR and MLR.

Results

A total of 552 patients (mean age 47.40, SD 17.09) were included, with 73.19% being male. Higher NLR at one-week post-cerebral contusion (adjusted OR = 4.19, 95%CI, 1.16 - 15.16, P = 0.029) and higher MLR at admission and at 24 h (5.80, 1.40 - 24.02, P = 0.015; 9.06, 1.45 - 56.54, P = 0.018, respectively) were significantly associated with a 6-month unfavorable prognosis after adjustment for other risk factors by multiple logistic regression. The NLR at admission and 24 hours, as well as the MLR at one week, were not significant predictors for a 6-month unfavorable prognosis. Based on receiver operating characteristic curve analysis, the optimal thresholds of NLR at 1 week and MLR at admission after cerebral contusion that best discriminated a unfavorable outcome at 6-month were 6.39 (81.60% sensitivity and 70.73% specificity) and 0.76 (55.47% sensitivity and 78.26% specificity), respectively.

Conclusion

NLR measured one week after cerebral contusion and MLR measured at admission may serve as predictive markers for a 6-month unfavorable prognosis. These ratios hold potential as parameters for risk stratification in patients with cerebral contusion, complementing established biomarkers in diagnosis and treatment. However, further prospective studies with larger cohorts are needed to validate these findings.

Matrix metalloproteinases as attractive therapeutic targets for chronic pain: A narrative review

Chronic pain constitutes an abnormal pain state that detrimentally affects the quality of life, daily activities, occupational performance, and stability of mood. Despite the prevalence of chronic pain, effective drugs with potent abirritation and minimal side effects remain elusive. Substantial studies have revealed aberrant activation of the matrix metalloproteinases (MMPs) in multiple chronic pain models. Additionally, emerging evidence has demonstrated that the downregulation of MMPs can alleviate chronic pain in diverse animal models, underscoring the unique and crucial role of MMPs in different stages and types of chronic pain. This review delves into the mechanistic insights and roles of MMPs in modulating chronic pain. The aberrant activation of MMPs has been linked to neuropathic pain through mechanisms involving myelin abnormalities in peripheral nerve and spinal dorsal horn (SDH), hyperexcitability of dorsal root ganglion (DRG) neurons, activation of N-methyl-d-aspartate receptors (NMDAR) and Ca2+-dependent signals, glial cell activation, and proinflammatory cytokines release. Different MMPs also contribute significantly to inflammatory pain and cancer pain. Furthermore, we summarized the substantial therapeutic potential of MMP pharmacological inhibitors across different types of chronic pain. Overall, our findings underscore the promising therapeutic prospects of MMPs targeting for managing chronic pain.

Contactin-associated protein-like 2 (CNTNAP2) mutations impair the essential α-secretase cleavages, leading to autism-like phenotypes

Mutations in the Contactin-associated protein-like 2 (CNTNAP2) gene are associated with autism spectrum disorder (ASD), and ectodomain shedding of the CNTNAP2 protein plays a role in its function. However, key enzymes involved in the C-terminal cleavage of CNTNAP2 remain largely unknown, and the effect of ASD-associated mutations on this process and its role in ASD pathogenesis remain elusive. In this report we showed that CNTNAP2 undergoes sequential cleavages by furin, ADAM10/17-dependent α-secretase and presenilin-dependent γ-secretase. We identified that the cleavage sites of ADAM10 and ADAM17 in CNTNAP2 locate at its C-terminal residue I79 and L96, and the main α-cleavage product C79 by ADAM10 is required for the subsequent γ-secretase cleavage to generate CNTNAP2 intracellular domain (CICD). ASD-associated CNTNAP2 mutations impair the α-cleavage to generate C79, and the inhibition leads to ASD-like repetitive and social behavior abnormalities in the Cntnap2-I1254T knock-in mice. Finally, exogenous expression of C79 improves autism-like phenotypes in the Cntnap2-I1254T knock-in and Cntnap2-/- knockout mice. This data demonstrates that the α-secretase is essential for CNTNAP2 processing and its function. Our study indicates that inhibition of the cleavage by pathogenic mutations underlies ASD pathogenesis, and upregulation of its C-terminal fragments could have therapeutical potentials for ASD treatment.

Metalloproteinases as Biomarkers and Sociomarkers in Human Health and Disease

Metalloproteinases (MPs) are zinc-dependent enzymes with proteolytic activity and a variety of functions in the pathophysiology of human diseases. The main objectives of this review are to analyze a specific family of MPs, the matrix metalloproteinases (MMPs), in the most common chronic and complex diseases that affect patients' social lives and to better understand the nature of the associations between MMPs and the psychosocial environment. In accordance with the PRISMA extension for a scoping review, an examination was carried out. A collection of 24 studies was analyzed, focusing on the molecular mechanisms of MMP and their connection to the manifestation of social aspects in human disease. The complexity of the relationship between MMP and social problems is presented via an interdisciplinary approach based on complexity paradigm as a new approach for conceptualizing knowledge in health research. Finally, two implications emerge from the study: first, the psychosocial states of individuals have a profound impact on their overall health and disease conditions, which implies the importance of adopting a holistic perspective on human well-being, encompassing both physical and psychosocial aspects. Second, the use of MPs as biomarkers may provide physicians with valuable tools for a better understanding of disease when used in conjunction with "sociomarkers" to develop mathematical predictive models.

Urine MMP7 as a kidney injury biomarker

Matrix metalloproteinase 7 (MMP-7) is a secreted endopeptidase involved in the degradation of extracellular matrix components and the activation of cytokines and growth factors. The regulation of MMP-7 can be transcriptionally regulated by AP-1 or Wnt/β-catenin or post-translationally by proteolytic activation. MMP-7 expression is low or absent in the healthy kidney, but is significantly upregulated in kidney injury, including AKI and CKD. The function of MMP-7 in kidney disease may differ for CKD and AKI; it may have a profibrotic role in CKD and an anti-apoptotic and regenerative function in AKI. Additionally, the potential of MMP-7 as a biomarker has been studied in different kidney diseases, and the results are promising. Recently, combined unbiased kidney proteomics and transcriptomics approaches identified kidney MMP-7 as the protein having the strongest association with both fibrosis and eGFR and confirmed the predictive role of plasma MMP-7 levels for kidney function decline in over 11 000 individuals. Additionally, urinary MMP-7, combined with urinary cystatin C (CysC) and retinol binding protein (RBP) was reported to provide information on tubular injury in focal segmental glomerulosclerosis and minimal change disease. We now present an overview of research on MMP-7 expression and function in kidney diseases and discuss its potential as a biomarker of kidney diseases.

Minding the Gap: Exploring Neuroinflammatory and Microglial Sex Differences in Alzheimer's Disease

Research into Alzheimer's Disease (AD) describes a link between AD and the resident immune cells of the brain, the microglia. Further, this suspected link is thought to have underlying sex effects, although the mechanisms of these effects are only just beginning to be understood. Many of these insights are the result of policies put in place by funding agencies such as the National Institutes of Health (NIH) to consider sex as a biological variable (SABV) and the move towards precision medicine due to continued lackluster therapeutic options. The purpose of this review is to provide an updated assessment of the current research that summarizes sex differences and the research pertaining to microglia and their varied responses in AD.

Multi-omics analysis of bone marrow mesenchymal stem cell differentiation differences in osteoporosis

Osteoporosis is a systemic skeletal disease characterized by low bone mass and degradation of bone tissue microarchitecture, leading to enhanced bone fragility and increased fracture risk. However, the pathogenesis of osteoporosis is unclear. Our results showed that BMSCs dervied from ovariectomized rats had a higher capacity for osteogenesis and lipogenic differentiation compared to the control group. In the meantime, we identified a total of 205 differentially expressed proteins and 2294 differentially expressed genes in BMSCs isolated from ovariectomized rats by proteomics analysis and transcriptome sequencing, respectively. These differentially expressed proteins and genes were mainly involved in ECM-receptor interaction signaling pathway. We speculate that BMSCs derived from ovariectomized rats have a higher potential for bone formation because expression of ECM collagen or genes encoding collagen in the bone ECM in BMSCs isolated from ovariectomized rats are increased compared with that from control group, which provided the prerequisite for the increased bone turnover effect. To conclusion, our results may provid new ideas for further research on the pathogenesis of osteoporosis.

Thrombin-Induced Microglia Activation Modulated through Aryl Hydrocarbon Receptors

Thrombin is a multifunctional serine protein which is closely related to neurodegenerative disorders. The Aryl hydrocarbon receptor (AhR) is well expressed in microglia cells involving inflammatory disorders of the brain. However, it remains unclear as to how modulation of AhR expression by thrombin is related to the development of neurodegeneration disorders. In this study, we investigated the role of AhR in the development of thrombin-induced neurodegenerative processes, especially those concerning microglia. The primary culture of either wild type or AhR deleted microglia, as well as BV-2 cell lines, was used for an in vitro study. Hippocampal slice culture and animals with either wild type or with AhR deleted were used for the ex vivo and in vivo studies. Simulations of ligand protein docking showed a strong integration between the thrombin and AhR. In thrombin-triggered microglia cells, deleting AhR escalated both the NO release and iNOS expression. Such effects were abolished by the administration of the AhR agonist. In thrombin-activated microglia cells, downregulating AhR increased the following: vascular permeability, pro-inflammatory genetic expression, MMP-9 activity, and the ratio of M1/M2 phenotype. In the in vivo study, thrombin induced the activation of microglia and their volume, thereby contributing to the deterioration of neurobehavior. Deleting AhR furthermore aggravated the response in terms of impaired neurobehavior, increasing brain edema, aggregating microglia, and increasing neuronal death. In conclusion, thrombin caused the activation of microglia through increased vessel permeability, expression of inflammatory response, and phenotype of M1 microglia, as well the MMP activity. Deleting AhR augmented the above detrimental effects. These findings indicate that the modulation of AhR is essential for the regulation of thrombin-induced brain damages and that the AhR agonist may harbor the potentially therapeutic effect in thrombin-induced neurodegenerative disorder.

Strategic outline of interventions targeting extracellular matrix for promoting healthy longevity

The extracellular matrix (ECM), composed of interlinked proteins outside of cells, is an important component of the human body that helps maintain tissue architecture and cellular homeostasis. As people age, the ECM undergoes changes that can lead to age-related morbidity and mortality. Despite its importance, ECM aging remains understudied in the field of geroscience. In this review, we discuss the core concepts of ECM integrity, outline the age-related challenges and subsequent pathologies and diseases, summarize diagnostic methods detecting a faulty ECM, and provide strategies targeting ECM homeostasis. To conceptualize this, we built a technology research tree to hierarchically visualize possible research sequences for studying ECM aging. This strategic framework will hopefully facilitate the development of future research on interventions to restore ECM integrity, which could potentially lead to the development of new drugs or therapeutic interventions promoting health during aging.

Preclinical Assessment of ADAM9-Responsive Mesoporous Silica Nanoparticles for the Treatment of Pancreatic Cancer

Pancreatic adenocarcinoma (PDAC) remains largely refractory to chemotherapeutic treatment regimens and, consequently, has the worst survival rate of all cancers. The low efficacy of current treatments results largely from toxicity-dependent dose limitations and premature cessation of therapy. Recently, targeted delivery approaches that may reduce off-target toxicities have been developed. In this paper, we present a preclinical evaluation of a PDAC-specific drug delivery system based on mesoporous silica nanoparticles (MSNs) functionalized with a protease linker that is specifically cleaved by PDAC cells. Our previous work demonstrated that ADAM9 is a PDAC-enriched protease and that paclitaxel-loaded ADAM9-responsive MSNs effectively kill PDAC cells in vitro. Here, we show that paclitaxel-loaded ADAM9-MSNs result in off-target cytotoxicity in clinically relevant models, which spurred the development of optimized ADAM9-responsive MSNs (OPT-MSNs). We found that these OPT-MSNs still efficiently kill PDAC cells but, as opposed to free paclitaxel, do not induce death in neuronal or bone marrow cells. In line with these in vitro data, paclitaxel-loaded OPT-MSNs showed reduced organ damage and leukopenia in a preclinical PDAC xenograft model. However, no antitumor response was observed upon OPT-MSN administration in vivo. The poor in vivo antitumor activity of OPT-MSNs despite efficient antitumor effects in vitro highlights that although MSN-based tumor-targeting strategies may hold therapeutic potential, clinical translation does not seem as straightforward as anticipated.

Therapeutic administration of mouse mast cell protease 6 improves functional recovery after traumatic spinal cord injury in mice by promoting remyelination and reducing glial scar formation

Traumatic spinal cord injury (SCI) most often leads to permanent paralysis due to the inability of axons to regenerate in the adult mammalian central nervous system (CNS). In the past, we have shown that mast cells (MCs) improve the functional outcome after SCI by suppressing scar tissue formation at the lesion site via mouse mast cell protease 6 (mMCP6). In this study, we investigated whether recombinant mMCP6 can be used therapeutically to improve the functional outcome after SCI. Therefore, we applied mMCP6 locally via an intrathecal catheter in the subacute phase after a spinal cord hemisection injury in mice. Our findings showed that hind limb motor function was significantly improved in mice that received recombinant mMCP6 compared with the vehicle-treated group. In contrast to our previous findings in mMCP6 knockout mice, the lesion size and expression levels of the scar components fibronectin, laminin, and axon-growth-inhibitory chondroitin sulfate proteoglycans were not affected by the treatment with recombinant mMCP6. Surprisingly, no difference in infiltration of CD4+ T cells and reactivity of Iba-1+ microglia/macrophages at the lesion site was observed between the mMCP6-treated mice and control mice. Additionally, local protein levels of the pro- and anti-inflammatory mediators IL-1β, IL-2, IL-4, IL-6, IL-10, TNF-α, IFNγ, and MCP-1 were comparable between the two treatment groups, indicating that locally applied mMCP6 did not affect inflammatory processes after injury. However, the increase in locomotor performance in mMCP6-treated mice was accompanied by reduced demyelination and astrogliosis in the perilesional area after SCI. Consistently, we found that TNF-α/IL-1β-astrocyte activation was decreased and that oligodendrocyte precursor cell (OPC) differentiation was increased after recombinant mMCP6 treatment in vitro. Mechanistically, this suggests effects of mMCP6 on reducing astrogliosis and improving (re)myelination in the spinal cord after injury. In conclusion, these data show for the first time that recombinant mMCP6 is therapeutically active in enhancing recovery after SCI.

Sex-specific associations of matrix metalloproteinases in Alzheimer's disease

INTRODUCTION

Alzheimer's disease (AD) can be characterised in vivo by biomarkers reflecting amyloid-β (Aβ) and tau pathology. However, there is a need for biomarkers reflecting additional pathological pathways. Matrix metalloproteinases (MMPs) have recently been highlighted as candidate biomarkers for sex-specific mechanisms and progression in AD.

METHODS

In this cross-sectional study, we investigated nine MMPs and four tissue inhibitors of metalloproteinases (TIMPs) in the cerebrospinal fluid of 256 memory clinic patients with mild cognitive impairment or dementia due to AD and 100 cognitively unimpaired age-matched controls. We studied group differences in MMP/TIMP levels and examined the associations with established markers of Aβ and tau pathology as well as disease progression. Further, we studied sex-specific interactions.

RESULTS

MMP-10 and TIMP-2 levels differed significantly between the memory clinic patients and the cognitively unimpaired controls. Furthermore, MMP- and TIMP-levels were generally strongly associated with tau biomarkers, whereas only MMP-3 and TIMP-4 were associated with Aβ biomarkers; these associations were sex-specific. In terms of progression, we found a trend towards higher MMP-10 at baseline predicting more cognitive and functional decline over time exclusively in women.

CONCLUSION

Our results support the use of MMPs/TIMPs as markers of sex differences and progression in AD. Our findings show sex-specific effects of MMP-3 and TIMP-4 on amyloid pathology. Further, this study highlights that the sex-specific effects of MMP-10 on cognitive and functional decline should be studied further if MMP-10 is to be used as a prognostic biomarker for AD.

A novel regulator in Alzheimer's disease progression: The astrocyte-derived extracellular vesicles

Alzheimer's disease (AD) is known as an age-related irreversible neurodegenerative disease. AD seriously endangers the health of the elderly, but there is still no effective treatment. In the past several decades, the significant role of astrocytes in the process of AD has been universally acknowledged. In addition, extracellular vesicles (EVs) have been recognized as an essential mediator in intercellular communication and participate in various pathophysiological processes by carrying and transporting diverse cargoes. Moreover, specific conditions and stimuli can modulate the amount and properties of astrocyte-derived EVs (ADEVs) to affect AD progression. Thus, recent studies focused on the involvement of ADEVs in the pathogenesis of AD and the potential application of ADEVs in the diagnosis and treatment of AD, which provides a new direction and possibility for revealing the mystery of AD. Interestingly, it can be concluded that ADEVs have both pathogenic and protective effects in the process of AD through a comprehensive generalization. In this review, we aim to summarize the multi-faces of ADEVs effects on AD development, which can provide a novel strategy to investigate the underlying mechanism in AD. We also summarize the current ADEVs clinically relevant studies to raise the potential use of ADEVs in the discovery of novel biomarkers for diagnosis and therapeutic targets for AD.

Dysregulation of Synaptic Plasticity Markers in Schizophrenia

Schizophrenia is a mental disorder characterized by cognitive impairment resulting in compromised quality of life. Since the regulation of synaptic plasticity has functional implications in various aspects of cognition such as learning, memory, and neural circuit maturation, the dysregulation of synaptic plasticity is considered as a pathobiological feature of schizophrenia. The findings from our recently concluded studies indicate that there is an alteration in levels of synaptic plasticity markers such as neural cell adhesion molecule-1 (NCAM-1), Neurotropin-3 (NT-3) and Matrix-mettaloproteinase-9 (MMP-9) in schizophrenia patients. The objective of the present article is to review the role of markers of synaptic plasticity in schizophrenia. PubMed database (http;//www.ncbi.nlm.nih.gov/pubmed) was used to perform an extensive literature search using the keywords schizophrenia and synaptic plasticity. We conclude that markers of synaptic plasticity are altered in schizophrenia and may lead to complications of schizophrenia including cognitive dysfunction.

CD147 and MMPs as key factors in physiological and pathological processes

Cluster of differentiation 147 (CD147) or extracellular matrix metalloproteinase inducer (EMMPRIN) is a transmembrane glycoprotein that induces the synthesis of matrix metalloproteinases (MMPs). MMPs, as zinc-dependent proteases and versatile enzymes, play critical roles in the degradation of the extracellular matrix (ECM) components, cleaving of the receptors of cellular surfaces, signaling molecules, and other precursor proteins, which may lead to attenuation or activation of such targets. CD147 and MMPs play essential roles in physiological and pathological conditions and any disorder in the expression, synthesis, or function of CD147 and MMPs may be associated with various types of disease. In this review, we have focused on the roles of CD147 and MMPs in some major physiological and pathological processes.

Chloride Intracellular Channel Protein 2 Promotes Microglial Invasion: A Link to Microgliosis in the Parkinson's Disease Brain

Activated microglia potentially cause neurodegeneration in Parkinson's disease (PD). Matrix metalloproteinase (MMP)-9 plays a crucial role in the pathogenesis of PD, but the modulator of microglial release of MMP-9 remains obscure. Given the modulatory effect of chloride intracellular channel protein 2 (CLIC2) on MMPs, we aimed to determine the role of CLIC2 in regulating microglial MMP expression and activation. We found that CLIC2 is expressed in microglia and neurons in rat brain tissue and focused on the function of CLIC2 in primary cultured microglia. Exposure to recombinant CLIC2 protein enhanced microglial invasion activity, and its knockdown abolished this activity. Moreover, increased activation of MMP-9 was confirmed by the addition of the CLIC2 protein, and CLIC2 knockdown eliminated this activation. Additionally, increased expression of CLIC2 was observed in PD-modeled tissue. In conclusion, CLIC2 increases MMP-9 activity in the microglia, which are involved in PD pathogenesis.

A Review of the Influence of Various Extraction Techniques and the Biological Effects of the Xanthones from Mangosteen (Garcinia mangostana L.) Pericarps

Xanthones are significant bioactive compounds and secondary metabolites in mangosteen pericarps. A xanthone is a phenolic compound and versatile scaffold that consists of a tricyclic xanthene-9-one structure. A xanthone may exist in glycosides, aglycones, monomers or polymers. It is well known that xanthones possess a multitude of beneficial properties, including antioxidant activity, anti-inflammatory activity, and antimicrobial properties. Additionally, xanthones can be used as raw material and/or an ingredient in many food, pharmaceutical, and cosmetic applications. Although xanthones can be used in various therapeutic and functional applications, their properties and stability are determined by their extraction procedures. Extracting high-quality xanthones from mangosteen with effective therapeutic effects could be challenging if the extraction method is insufficient. Although several extraction processes are in use today, their efficiency has not yet been rigorously evaluated. Therefore, selecting an appropriate extraction procedure is imperative to recover substantial yields of xanthones with enhanced functionality from mangosteens. Hence, the present review will assist in establishing a precise scenario for finding the most appropriate extraction method for xanthones from mangosteen pericarp by critically analyzing various conventional and unconventional extraction methods and their ability to preserve the stability and biological effects of xanthones.

Matrix Metalloproteinases and Glaucoma

Matrix metalloproteinases (MMPs) are enzymes that decompose extracellular matrix (ECM) proteins. MMPs are thought to play important roles in cellular processes, such as cell proliferation, differentiation, angiogenesis, migration, apoptosis, and host defense. MMPs are distributed in almost all intraocular tissues and are involved in physiological and pathological mechanisms of the eye. MMPs are also associated with glaucoma, a progressive neurodegenerative disease of the eyes. MMP activity affects intraocular pressure control and apoptosis of retinal ganglion cells, which are the pathological mechanisms of glaucoma. It also affects the risk of glaucoma development based on genetic pleomorphism. In addition, MMPs may affect the treatment outcomes of glaucoma, including the success rate of surgical treatment and side effects on the ocular surface due to glaucoma medications. This review discusses the various relationships between MMP and glaucoma.

Insights Into the Role of Platelet-Derived Growth Factors: Implications for Parkinson’s Disease Pathogenesis and Treatment

Parkinson’s disease (PD), the second most common neurodegenerative disease after Alzheimer’s disease, commonly occurs in the elderly population, causing a significant medical and economic burden to the aging society worldwide. At present, there are few effective methods that achieve satisfactory clinical results in the treatment of PD. Platelet-derived growth factors (PDGFs) and platelet-derived growth factor receptors (PDGFRs) are important neurotrophic factors that are expressed in various cell types. Their unique structures allow for specific binding that can effectively regulate vital functions in the nervous system. In this review, we summarized the possible mechanisms by which PDGFs/PDGFRs regulate the occurrence and development of PD by affecting oxidative stress, mitochondrial function, protein folding and aggregation, Ca2+ homeostasis, and cell neuroinflammation. These modes of action mainly depend on the type and distribution of PDGFs in different nerve cells. We also summarized the possible clinical applications and prospects for PDGF in the treatment of PD, especially in genetic treatment. Recent advances have shown that PDGFs have contradictory roles within the central nervous system (CNS). Although they exert neuroprotective effects through multiple pathways, they are also associated with the disruption of the blood–brain barrier (BBB). Our recommendations based on our findings include further investigation of the contradictory neurotrophic and neurotoxic effects of the PDGFs acting on the CNS.

Expression of matrix metalloproteinases and tissue inhibitors of metalloproteinases in the hippocampus of lithium-pilocarpine-induced acute epileptic rats

BACKGROUND

Epilepsy is characterised by abnormal neuronal discharges, including aberrant expression of extracellular matrix (ECM) components and synaptic plasticity stabilisation. Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) interact to remodel the ECM in the central nervous system (CNS), to modulate synaptic plasticity in epileptogenesis.

METHODS AND RESULTS

In the present study, the expression of MMP activators (tPA and uPA), 10 MMPs, and 3 TIMPs was detected by western blot analysis and quantitative polymerase chain reaction (RT-qPCR) to assess their potential pathogenetic role in the epileptogenesis in the hippocampus of lithium-pilocarpine hydrochloride-induced epileptic rats. Our results showed that The expression of MMP7 and MMP14 was impeded in the hippocampus of lithium-pilocarpine-induced acute epileptic rats compared with that in controls. The transcriptional level of tPA was enhanced on day 1 post-seizure in the hippocampus, while the levels of several MMPs and TIMPs did not change on days 1 and 3 post-seizure compared with that in controls.

CONCLUSIONS

The expression of MMPs and TIMPs reflects a novel feature of epileptogenesis and may offer new perspectives for future therapeutic interventions.

Mechanotransduction: Exploring New Therapeutic Avenues in Central Nervous System Pathology

Cells are continuously exposed to physical forces and the central nervous system (CNS) is no exception. Cells dynamically adapt their behavior and remodel the surrounding environment in response to forces. The importance of mechanotransduction in the CNS is illustrated by exploring its role in CNS pathology development and progression. The crosstalk between the biochemical and biophysical components of the extracellular matrix (ECM) are here described, considering the recent explosion of literature demonstrating the powerful influence of biophysical stimuli like density, rigidity and geometry of the ECM on cell behavior. This review aims at integrating mechanical properties into our understanding of the molecular basis of CNS disease. The mechanisms that mediate mechanotransduction events, like integrin, Rho/ROCK and matrix metalloproteinases signaling pathways are revised. Analysis of CNS pathologies in this context has revealed that a wide range of neurological diseases share as hallmarks alterations of the tissue mechanical properties. Therefore, it is our belief that the understanding of CNS mechanotransduction pathways may lead to the development of improved medical devices and diagnostic methods as well as new therapeutic targets and strategies for CNS repair.

Matrix metalloproteinases and tissue inhibitors of metalloproteinases in murine β-coronavirus-induced neuroinflammation

Mouse hepatitis virus (MHV; m-β-CoV) serves as a useful model for studying the cellular factors involved in neuroinflammation. To understand the role of matrix metalloproteinases (MMPs) in neuroinflammation, brain tissues from m-β-CoV-infected mice were harvested at different days post-infection (d.p.i) and investigated for Mmp expression by RT-qPCR. Mmp-2, -3, -8, -12 showed significant mRNA upregulation peaking with viral replication between 5 and 6 d.p.i. Elevated levels of MMP regulator TIMP-1 are suggestive of a TIMP-1 mediated host antiviral response. Biological network assessment suggested a direct involvement of MMP-3, -8, -14 in facilitating peripheral leukocyte infiltrations. Flow cytometry confirmed the increased presence of NK cells, CD4⁺ and CD8⁺ T cells, neutrophils, and MHCII expressing cells in the m-β-CoV infected mice brain. Our study revealed that m-β-CoV upregulated Park7, RelA, Nrf2, and Hmox1 transcripts involved in ROS production and antioxidant pathways, describing the possible nexus between oxidative pathways, MMPs, and TIMP in m-β-CoV-induced neuroinflammation.

Deoxysphingolipids Upregulate MMP-1, Downregulate TIMP-1, and Induce Cytotoxicity in Human Schwann Cells

Sphingolipids are a heterogeneous class of lipids and essential components of the plasma membrane and plasma lipoproteins. Studies have shown that plasma deoxysphingolipid (DSL), a newly identified sphingolipid class, is increased in diabetic patients and associated with diabetic neuropathy. However, it remains unknown if there is a causal relationship between plasma DSL increase and diabetic neuropathy. Since matrix metalloproteinases (MMPs) play an important role in diabetic neuropathy by degrading extracellular matrix in the peripheral nervous system, we investigated the effect of DSLs on the expression of MMPs and tissue inhibitor of metalloproteinase (TIMPs), and cytotoxicity in human Schwann cells. We quantified protein secretion, gene expression, and collagenase activity, and performed cytotoxicity assays. Results showed that DSLs upregulated MMP-1, downregulated TIMP-1, and induced cytotoxicity in Schwann cells. Furthermore, we quantified DSLs in VLDL, LDL, HDL2, and HDL3 isolated from type 2 diabetes mellitus (T2DM) patients with or without neuropathy. Interestingly, lipidomic analysis showed that only HDL2 isolated from T2DM patients with neuropathy contains significantly higher level of DSLs than that isolated from T2DM patients without neuropathy. Additionally, results showed that HDL2 isolated from T2DM patients with neuropathy was more potent than that isolated from T2DM patients without neuropathy in upregulating MMP-1, downregulating TIMP-1, and stimulating collagenase activity in Schwann cell. Taken together, this study demonstrated for the first time a potential causal relationship between DSLs and diabetic neuropathy and that DSL-containing HDL2 from T2DM patients with neuropathy was more potent than that from T2DM patients without neuropathy in stimulating collagenase activity.

Dynamics of biomarkers across the stages of traumatic spinal cord injury - implications for neural plasticity and repair

BACKGROUND

Traumatic spinal cord injury (SCI) is a complex medical condition causing significant physical disability and psychological distress. While the adult spinal cord is characterized by poor regenerative potential, some recovery of neurological function is still possible through activation of neural plasticity mechanisms. We still have limited knowledge about the activation of these mechanisms in the different stages after human SCI.

OBJECTIVE

In this review, we discuss the potential role of biomarkers of SCI as indicators of the plasticity mechanisms at work during the different phases of SCI.

METHODS

An extensive review of literature related to SCI pathophysiology, neural plasticity and humoral biomarkers was conducted by consulting the PubMed database. Research and review articles from SCI animal models and SCI clinical trials published in English until January 2021 were reviewed. The selection of candidates for humoral biomarkers of plasticity after SCI was based on the following criteria: 1) strong evidence supporting involvement in neural plasticity (mandatory); 2) evidence supporting altered expression after SCI (optional).

RESULTS

Based on selected findings, we identified two main groups of potential humoral biomarkers of neural plasticity after SCI: 1) neurotrophic factors including: Brain derived neurotrophic factor (BDNF), Nerve growth factor (NGF), Neurotrofin-3 (NT-3), and Insulin-like growth factor 1 (IGF-1); 2) other factors including: Tumor necrosis factor-alpha (TNF-α), Matrix Metalloproteinases (MMPs), and MicroRNAs (miRNAs). Plasticity changes associated with these biomarkers often can be both adaptive (promoting functional improvement) and maladaptive. This dual role seems to be influenced by their concentrations and time-window during SCI.

CONCLUSIONS

Further studies of dynamics of biomarkers across the stages of SCI are necessary to elucidate the way in which they reflect the remodeling of neural pathways. A better knowledge about the mechanisms underlying plasticity could guide the selection of more appropriate therapeutic strategies to enhance positive spinal network reorganization.

Role of Matrix Metalloproteinases in Myelin Abnormalities and Mechanical Allodynia in Rodents with Diabetic Neuropathy

The treatment of diabetic neuropathic pain (DNP) is a major clinical challenge. The underlying mechanisms of diabetic neuropathy remain unclear, and treatment approaches are limited. Here, we report that the gelatinases MMP-9 and MMP-2 play a critical role in axonal demyelination and DNP in rodents. MMP-9 may contribute to streptozotocin (STZ)-induced DNP via inducing axonal demyelination and spinal central sensitization, while MMP-2 may serve as a negative regulator. In STZ-induced DNP rats, the activity of MMP-9 was increased, while MMP-2 was decreased in the dorsal root ganglion and spinal cord. Spinal inhibition of MMP-9, but not MMP-2, greatly suppressed the behavioral and neurochemical signs of DNP, while administration of MMP-2 alleviated mechanical allodynia. In mice, STZ treatment resulted in axonal demyelination in the peripheral sciatic nerves and spinal dorsal horn, in addition to mechanical allodynia. These neuropathic alterations were significantly reduced in MMP-9^-/- mice. Finally, systematic administration of α-lipoic acid significantly suppressed STZ-induced mechanical allodynia by inhibiting MMP-9 and rescuing MMP-2 activity. These findings support a new mechanism underlying the pathogenesis of diabetic neuropathy and suggest a potential target for DNP treatment. Gelatinases MMP-9 and MMP-2 play a critical role in the pathogenesis of diabetic neuropathy and may serve as a potential treatment target. MMP-9/2 underlies the mechanism of α-lipoic acid in diabetic neuropathy, providing a potential target for the development of novel analgesic and anti-inflammatory drugs.

Local and Systemic Expression Pattern of MMP-2 and MMP-9 in Complex Regional Pain Syndrome

Matrix metalloproteinases (MMP)-2 and MMP-9 play important roles in inflammation as well as in pain processes. For this reason, we compared the concentrations of these enzymes in skin and serum of patients with complex regional pain syndrome (CRPS), other pain diseases and healthy subjects. We analyzed ipsi- and contralateral skin biopsies of 18 CRPS patients, as well as in 10 pain controls and 9 healthy subjects. Serum samples were analyzed from 20 CRPS, 17 pain controls and 17 healthy subjects. All samples were analyzed with ELISA. Concentrations were then compared to clinical data as well as to quantitative sensory testing data.MMP-2 was increased in both ipsi- and contralateral skin biopsies of CRPS patients compared to healthy subjects. While low ipsilateral MMP-2 was associated with trophic changes, contralateral MMP-2 inversely correlated with the CRPS severity. MMP-9 was also locally increased in ipsilateral CRPS skin, and higher ipsi- and contralateral MMP-9 levels correlated with CRPS severity. We conclude that MMP-2 and MMP-9 are differently expressed depending on the clinical phenotype in CRPS. PERSPECTIVE: This article describes an upregulation of MMPs in CRPS and pain controls and shows different expression of MMP-2 and -9 depending on clinical phenotype in CRPS. These results provide evidence that MMP-2 and -9 play a key role in CRPS pathophysiology.

The matrix metalloproteinase inhibitor IPR-179 has antiseizure and antiepileptogenic effects

Matrix metalloproteinases (MMPs) are synthesized by neurons and glia and released into the extracellular space, where they act as modulators of neuroplasticity and neuroinflammatory agents. Development of epilepsy (epileptogenesis) is associated with increased expression of MMPs, and therefore, they may represent potential therapeutic drug targets. Using quantitative PCR (qPCR) and immunohistochemistry, we studied the expression of MMPs and their endogenous inhibitors tissue inhibitors of metalloproteinases (TIMPs) in patients with status epilepticus (SE) or temporal lobe epilepsy (TLE) and in a rat TLE model. Furthermore, we tested the MMP2/9 inhibitor IPR-179 in the rapid-kindling rat model and in the intrahippocampal kainic acid mouse model. In both human and experimental epilepsy, MMP and TIMP expression were persistently dysregulated in the hippocampus compared with in controls. IPR-179 treatment reduced seizure severity in the rapid-kindling model and reduced the number of spontaneous seizures in the kainic acid model (during and up to 7 weeks after delivery) without side effects while improving cognitive behavior. Moreover, our data suggest that IPR-179 prevented an MMP2/9-dependent switch-off normally restraining network excitability during the activity period. Since increased MMP expression is a prominent hallmark of the human epileptogenic brain and the MMP inhibitor IPR-179 exhibits antiseizure and antiepileptogenic effects in rodent epilepsy models and attenuates seizure-induced cognitive decline, it deserves further investigation in clinical trials.

Emerging roles of MT-MMPs in embryonic development

Membrane-type matrix metalloproteinases (MT-MMPs) are cell membrane-tethered proteinases that belong to the family of the MMPs. Apart from their roles in degradation of the extracellular milieu, MT-MMPs are able to activate through proteolytic processing at the cell surface distinct molecules such as receptors, growth factors, cytokines, adhesion molecules, and other pericellular proteins. Although most of the information regarding these enzymes comes from cancer studies, our current knowledge about their contribution in distinct developmental processes occurring in the embryo is limited. In this review, we want to summarize the involvement of MT-MMPs in distinct processes during embryonic morphogenesis, including cell migration and proliferation, epithelial-mesenchymal transition, cell polarity and branching, axon growth and navigation, synapse formation, and angiogenesis. We also considered information about MT-MMP functions from studies assessed in pathological conditions and compared these data with those relevant for embryonic development.

Cyclooxygenase Inhibition Alters Proliferative, Migratory, and Invasive Properties of Human Glioblastoma Cells In Vitro

Prostaglandin E₂ (PGE₂) is known to increase glioblastoma (GBM) cell proliferation and migration while cyclooxygenase (COX) inhibition decreases proliferation and migration. The present study investigated the effects of COX inhibitors and PGE₂ receptor antagonists on GBM cell biology. Cells were grown with inhibitors and dose response, viable cell counting, flow cytometry, cell migration, gene expression, Western blotting, and gelatin zymography studies were performed. The stimulatory effects of PGE₂ and the inhibitory effects of ibuprofen (IBP) were confirmed in GBM cells. The EP2 and EP4 receptors were identified as important mediators of the actions of PGE₂ in GBM cells. The concomitant inhibition of EP2 and EP4 caused a significant decrease in cell migration which was not reverted by exogenous PGE₂. In T98G cells exogenous PGE₂ increased latent MMP2 gelatinolytic activity. The inhibition of COX1 or COX2 caused significant alterations in MMP2 expression and gelatinolytic activity in GBM cells. These findings provide further evidence for the importance of PGE₂ signalling through the EP2 and the EP4 receptor in the control of GBM cell biology. They also support the hypothesis that a relationship exists between COX1 and MMP2 in GBM cells which merits further investigation as a novel therapeutic target for drug development.

Transcriptional networks identify synaptotagmin-like 3 as a regulator of cortical neuronal migration during early neurodevelopment

Human brain development is a complex process involving neural proliferation, differentiation, and migration that are directed by many essential cellular factors and drivers. Here, using the NetBID2 algorithm and developing human brain RNA sequencing dataset, we identify synaptotagmin-like 3 (SYTL3) as one of the top drivers of early human brain development. Interestingly, SYTL3 exhibits high activity but low expression in both early developmental human cortex and human embryonic stem cell (hESC)-derived neurons. Knockout of SYTL3 (SYTL3-KO) in human neurons or knockdown of Sytl3 in embryonic mouse cortex markedly promotes neuronal migration. SYTL3-KO causes an abnormal distribution of deep-layer neurons in brain organoids and reduces presynaptic neurotransmitter release in hESC-derived neurons. We further demonstrate that SYTL3-KO-accelerated neuronal migration is modulated by high expression of matrix metalloproteinases. Together, based on bioinformatics and biological experiments, we identify SYTL3 as a regulator of cortical neuronal migration in human and mouse developing brains.

Novel matrix metalloproteinase inhibitors: an updated patent review (2014 - 2020)

Introduction: Matrix MetalloProteinases (MMPs) are key enzymes in several pathophysiological processes connected to the extracellular matrix (ECM) degradation. Earlier clinical trials evaluating broad spectrum MMP inhibitors as cancer therapeutics failed to succeed, resulting in toxic side effects, such as musculoskeletal pain and inflammation, due to poor selectivity. As it is now recognized that some MMPs are essential for tumor progression and metastasis, but others play host-protective functions, selective MMP inhibitors are needed, and their interest has grown also for therapeutic applications beyond cancer, such as infectious, inflammatory and neurological diseases. Areas covered: This updated review describes patents concerning MMP inhibitors published within January 2014 and June 2020, with therapeutic applications spanning from cancer to inflammatory and neurological disorders. Expert opinion: Although the number of patents has decreased with respect to the previous decade, new applications provide selective matrix metalloproteinase inhibitors for therapeutic treatments beyond cancer. For several applications, the need of selective inhibitors resulted in the development of new non-hydroxamate compounds, paving the way towards a renewed interest towards MMPs as therapeutic targets. In particular, inhibitors able to cross the blood-brain barrier have been disclosed and proposed for the treatment of neurological conditions, infections, wound healing and cancer.

Multifaceted Role of Matrix Metalloproteinases in Neurodegenerative Diseases: Pathophysiological and Therapeutic Perspectives

Neurodegeneration is the pathological condition, in which the nervous system or neuron loses its structure, function, or both, leading to progressive degeneration or the death of neurons, and well-defined associations of tissue system, resulting in clinical manifestations. Neuroinflammation has been shown to precede neurodegeneration in several neurodegenerative diseases (NDs). No drug is yet known to delay or treat neurodegeneration. Although the etiology and potential causes of NDs remain widely indefinable, matrix metalloproteinases (MMPs) evidently have a crucial role in the progression of NDs. MMPs, a protein family of zinc (Zn²⁺)-containing endopeptidases, are pivotal agents that are involved in various biological and pathological processes in the central nervous system (CNS). The current review delineates the several emerging evidence demonstrating the effects of MMPs in the progression of NDs, wherein they regulate several processes, such as (neuro)inflammation, microglial activation, amyloid peptide degradation, blood brain barrier (BBB) disruption, dopaminergic apoptosis, and α-synuclein modulation, leading to neurotoxicity and neuron death. Published papers to date were searched via PubMed, MEDLINE, etc., while using selective keywords highlighted in our manuscript. We also aim to shed a light on pathophysiological effect of MMPs in the CNS and focus our attention on its detrimental and beneficial effects in NDs, with a special focus on Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), multiple sclerosis (MS), and Huntington's disease (HD), and discussed various therapeutic strategies targeting MMPs, which could serve as potential modulators in NDs. Over time, several agents have been developed in order to overcome challenges and open up the possibilities for making selective modulators of MMPs to decipher the multifaceted functions of MMPs in NDs. There is still a greater need to explore them in clinics.

Immunopathogenicity of Acanthamoeba spp. in the Brain and Lungs

Free-living amoebas, including Acanthamoeba spp., are widely distributed in soil, water, and air. They are capable of causing granulomatous amebic encephalitis, Acanthamoeba pneumonia, Acanthamoeba keratitis, and disseminated acanthamoebiasis. Despite low occurrence worldwide, the mortality rate of Acanthamoeba spp. infections is very high, especially in immunosuppressed hosts. Acanthamoeba infections are a medical problem, owing to limited improvement in diagnostics and treatment, which is associated with incomplete knowledge of pathophysiology, pathogenesis, and the host immune response against Acanthamoeba spp. infection. The aim of this review is to present the biochemical and molecular mechanisms of Acanthamoeba spp.-host interactions, including the expression of Toll-like receptors, mechanisms of an immune response, the activity of metalloproteinases, the secretion of antioxidant enzymes, and the expression and activity of cyclooxygenases. We show the relationship between Acanthamoeba spp. and the host at the cellular level and host defense reactions that lead to changes in the selected host's organs.

Matrix Metalloproteinase 9 Blood Alterations in Patients With Schizophrenia Spectrum Disorders: A Systematic Review and Meta-Analysis

BACKGROUND

Matrix metalloproteinase 9 (MMP-9), an extracellular network protease implicated in glutamatergic signaling, may be part of the pathophysiology of schizophrenia spectrum disorders (SSD).

METHODS

We performed a systematic review in PubMed/Embase until July 15, 2020, conducting a random-effects meta-analysis of studies comparing MMP-9 blood levels in SSD vs healthy controls (HCs) and psychiatric controls (PCs), calculating between-group differences in standardized mean differences (SMDs) ± 95% confidence intervals (CIs). Meta-regression analyses included sex, age, illness duration, antipsychotic dose, and Positive and Negative Syndrome Scale (PANSS) total/subscales. Subgroup analyses included first-episode patients (FEP) vs non-FEP, each vs HCs and vs PCs, and blood sample type. Study quality was assessed using the Newcastle-Ottawa scale.

RESULTS

Four, five, and two trials were rated as high, fair, and low quality. In 11 studies (n = 1443), 643 patients (age = 36.7 ± 14.1 years, females = 42.9%) were compared with HCs (n = 631), with 4 studies including also 169 PCs. MMP-9 levels were higher in SSD vs HCs (SMD = 0.52, 95%CI = 0.20-0.85, P = .002), but not in PCs vs HCs (n = 132, after removing one implausible outlier [SMD = 0.33, 95%CI = -0.16 to 0.85, P = .082]). MMP-9 differences between SSD and HCs were associated with higher PANSS total (coefficient = 0.02, 95%CI = 0.01-0.02, P < .001), PANSS positive (coefficient = 0.08, 95%CI = 0.02-0.13, P = .006), and PANSS general scores (coefficient = 0.02, 95%CI = 0.01-0.03, P < .001). MMP-9 level differences vs HCs did not vary significantly between FEP (n = 103, SMD = 0.44, 95%CI = 0.15-0.72, P = .71) and non-FEP patients (n = 466, SMD = 0.59, 95%CI = 0.38-0.80; P = .34) (FEP vs non-FEP: P = .39). In four high-quality studies, MMP-9 levels remained significantly higher in SSD vs HCs (SMD = 0.82, 95%CI = 0.03-1.61).

CONCLUSIONS

Findings suggest MMP-9 upregulation in SSD, requiring further validation and understanding of related pathways.

Scrap and Build for Functional Neural Circuits: Spatiotemporal Regulation of Dendrite Degeneration and Regeneration in Neural Development and Disease

Dendrites are cellular structures essential for the integration of neuronal information. These elegant but complex structures are highly patterned across the nervous system but vary tremendously in their size and fine architecture, each designed to best serve specific computations within their networks. Recent in vivo imaging studies reveal that the development of mature dendrite arbors in many cases involves extensive remodeling achieved through a precisely orchestrated interplay of growth, degeneration, and regeneration of dendritic branches. Both degeneration and regeneration of dendritic branches involve precise spatiotemporal regulation for the proper wiring of functional networks. In particular, dendrite degeneration must be targeted in a compartmentalized manner to avoid neuronal death. Dysregulation of these developmental processes, in particular dendrite degeneration, is associated with certain types of pathology, injury, and aging. In this article, we review recent progress in our understanding of dendrite degeneration and regeneration, focusing on molecular and cellular mechanisms underlying spatiotemporal control of dendrite remodeling in neural development. We further discuss how developmental dendrite degeneration and regeneration are molecularly and functionally related to dendrite remodeling in pathology, disease, and aging.

Dynamic change of MMP-9 in diabetic stroke visualized by optical imaging and treated with CD28 superagonist

By utilizing NIRF imaging, diabetic stroke mice were visualized with a trend of higher levels of MMP-9 than wild-type mice. CD28 SA down-regulated the expression of MMP-9 and represents a potential treatment to diabetic stroke.

The Monocyte-to-Lymphocyte Ratio at Hospital Admission Is a Novel Predictor for Acute Traumatic Intraparenchymal Hemorrhage Expansion after Cerebral Contusion

PURPOSE

To explore the potential of monocyte-to-lymphocyte ratio (MLR) at hospital admission for predicting acute traumatic intraparenchymal hematoma (tICH) expansion in patients with cerebral contusion. Patients and Methods. This multicenter, observational study included patients with available at-hospital admission (baseline) and follow-up computed tomography for volumetric analysis (retrospective development cohort: 1146 patients; prospective validation cohort: 207 patients). Semiautomated software assessed tICH expansion (defined as ≥33% or 5 mL absolute growth). MLR was acquired from routine blood tests upon admission. We constructed two predictive models: basic combined model of clinical and imaging variables and MLR combined model of both MLR and other variables in the basic model. Receiver operating characteristic (ROC) analysis and decision curve analysis (DCA) were used to estimate the performance of MLR for predicting acute tICH expansion.

RESULTS

MLR was significantly larger in patients with acute tICH expansion compared to those without acute tICH expansion (mean [SD], 1.08 [1.05] vs. 0.59 [0.37], P < 0.001). A nonlinear positive relationship between MLR and the incidence of acute tICH expansion was observed. Multivariate logistic regression indicated MLR as an independent risk factor for acute tICH expansion (odds ratio (OR), 5.88; 95% confidence interval (CI), 4.02-8.61). The power of the multivariate model for predicting acute tICH expansion was substantially improved with the inclusion of MLR (AUC 0.86 vs. AUC 0.74, P < 0.001), as was also observed in an external validation cohort (AUC 0.83 vs. AUC 0.71, P < 0.001). The net benefit of MLR model was higher between threshold probabilities of 20-100% in DCA. For clinical application, a nomogram derived from the multivariate model with MLR was introduced. In addition, MLR was positively associated with 6-month unfavorable outcome.

CONCLUSION

MLR is a novel predictor for traumatic parenchymatous hematoma expansion. A nomogram derived from the MLR model may provide an easy-to-use tool for predicting acute tICH expansion and promoting the individualized treatment of patients with hemorrhagic cerebral contusion. MLR is associated with long-term outcome after cerebral contusion.

Treating brain diseases using systemic parenterally-administered protein therapeutics: Dysfunction of the brain barriers and potential strategies

The parenteral administration of protein therapeutics is increasingly gaining importance for the treatment of human diseases. However, the presence of practically impermeable blood-brain barriers greatly restricts access of such pharmaceutics to the brain. Treating brain disorders with proteins thus remains a great challenge, and the slow clinical translation of these therapeutics may be largely ascribed to the lack of appropriate brain delivery system. Exploring new approaches to deliver proteins to the brain by circumventing physiological barriers is thus of great interest. Moreover, parallel advances in the molecular neurosciences are important for better characterizing blood-brain interfaces, particularly under different pathological conditions (e.g., stroke, multiple sclerosis, Parkinson's disease, and Alzheimer's disease). This review presents the current state of knowledge of the structure and the function of the main physiological barriers of the brain, the mechanisms of transport across these interfaces, as well as alterations to these concomitant with brain disorders. Further, the different strategies to promote protein delivery into the brain are presented, including the use of molecular Trojan horses, the formulation of nanosystems conjugated/loaded with proteins, protein-engineering technologies, the conjugation of proteins to polymers, and the modulation of intercellular junctions. Additionally, therapeutic approaches for brain diseases that do not involve targeting to the brain are presented (i.e., sink and scavenging mechanisms).

Mild hypoxia triggers transient blood-brain barrier disruption: a fundamental protective role for microglia

We recently demonstrated that when mice are exposed to chronic mild hypoxia (CMH, 8% O2), blood vessels in the spinal cord show transient vascular leak that is associated with clustering and activation of microglia around disrupted vessels. Importantly, microglial depletion profoundly increased hypoxia-induced vascular leak, implying that microglia play a critical role maintaining vascular integrity in the hypoxic spinal cord. The goal of the current study was to examine if microglia play a similar vasculo-protective function in the brain. Employing extravascular fibrinogen leak as an index of blood-brain barrier (BBB) disruption, we found that CMH provoked transient vascular leak in cerebral blood vessels that was associated with activation and aggregation of Mac-1-positive microglia around leaky vessels. Interestingly, CMH-induced vascular leak showed regional selectivity, being much more prevalent in the brainstem and olfactory bulb than the cerebral cortex and cerebellum. Pharmacological depletion of microglia with the colony stimulating factor-1 receptor inhibitor PLX5622, had no effect under normoxic conditions, but markedly increased hypoxia-induced cerebrovascular leak in all regions examined. As in the spinal cord, this was associated with endothelial induction of MECA-32, a marker of leaky CNS endothelium, and greater loss of endothelial tight junction proteins. Brain regions displaying the highest levels of hypoxic-induced vascular leak also showed the greatest levels of angiogenic remodeling, suggesting that transient BBB disruption may be an unwanted side-effect of hypoxic-induced angiogenic remodeling. As hypoxia is common to a multitude of human diseases including obstructive sleep apnea, lung disease, and age-related pulmonary, cardiac and cerebrovascular dysfunction, our findings have important translational implications. First, they point to a potential pathogenic role of chronic hypoxia in triggering BBB disruption and subsequent neurological dysfunction, and second, they demonstrate an important protective role for microglia in maintaining vascular integrity in the hypoxic brain.

Protective Functions of Reactive Astrocytes Following Central Nervous System Insult

Astrocytes play important roles in numerous central nervous system disorders including autoimmune inflammatory, hypoxic, and degenerative diseases such as Multiple Sclerosis, ischemic stroke, and Alzheimer’s disease. Depending on the spatial and temporal context, activated astrocytes may contribute to the pathogenesis, progression, and recovery of disease. Recent progress in the dissection of transcriptional responses to varying forms of central nervous system insult has shed light on the mechanisms that govern the complexity of reactive astrocyte functions. While a large body of research focuses on the pathogenic effects of reactive astrocytes, little is known about how they limit inflammation and contribute to tissue regeneration. However, these protective astrocyte pathways might be of relevance for the understanding of the underlying pathology in disease and may lead to novel targeted approaches to treat autoimmune inflammatory and degenerative disorders of the central nervous system. In this review article, we have revisited the emerging concept of protective astrocyte functions and discuss their role in the recovery from inflammatory and ischemic disease as well as their role in degenerative disorders. Focusing on soluble astrocyte derived mediators, we aggregate the existing knowledge on astrocyte functions in the maintenance of homeostasis as well as their reparative and tissue-protective function after acute lesions and in neurodegenerative disorders. Finally, we give an outlook of how these mediators may guide future therapeutic strategies to tackle yet untreatable disorders of the central nervous system.

The blood-brain barrier is disrupted in Machado-Joseph disease/spinocerebellar ataxia type 3: evidence from transgenic mice and human post-mortem samples

Blood-brain barrier (BBB) disruption is a common feature in neurodegenerative diseases. However, BBB integrity has not been assessed in spinocerebellar ataxias (SCAs) such as Machado-Joseph disease/SCA type 3 (MJD/SCA3), a genetic disorder, triggered by polyglutamine-expanded ataxin-3. To investigate that, BBB integrity was evaluated in a transgenic mouse model of MJD and in human post-mortem brain tissues.

Firstly, we investigated the BBB permeability in MJD mice by: i) assessing the extravasation of the Evans blue (EB) dye and blood-borne proteins (e.g fibrinogen) in the cerebellum by immunofluorescence, and ii) in vivo Dynamic Contrast Enhanced-Magnetic Resonance Imaging (DCE-MRI). The presence of ataxin-3 aggregates in brain blood vessels and the levels of tight junction (TJ)-associated proteins were also explored by immunofluorescence and western blotting. Human brain samples were used to confirm BBB permeability by evaluating fibrinogen extravasation, co-localization of ataxin-3 aggregates with brain blood vessels and neuroinflammation.

In the cerebellum of the mouse model of MJD, there was a 5-fold increase in EB accumulation when compared to age-matched controls. Moreover, vascular permeability displayed a 13-fold increase demonstrated by DCE-MRI. These results were validated by the 2-fold increase in fibrinogen extravasation in transgenic animals comparing to controls. Interestingly, mutant ataxin-3 aggregates were detected in cerebellar blood vessels of transgenic mice, accompanied by alterations of TJ-associated proteins in cerebellar endothelial cells, namely a 29% decrease in claudin-5 oligomers and a 10-fold increase in an occludin cleavage fragment. These results were validated in post-mortem brain samples from MJD patients as we detected fibrinogen extravasation across BBB, the presence of ataxin-3 aggregates in blood vessels and associated microgliosis.

Altogether, our results prove BBB impairment in MJD/SCA3. These findings contribute for a better understanding of the disease mechanisms and opens the opportunity to treat MJD with medicinal products that in normal conditions would not cross the BBB.

[Proteolytic cleavage of neuroligins and functions of their cleavage products]

Neuroligin is a key protein that mediates synaptic development and maturation, and is closely related to neurodevelopmental diseases such as autism. In recent years, researchers have found that neuroligin can be hydrolyzed by various proteases at different stages of development, neuronal activities or pathological states of some neuropsychiatric diseases, thus affecting synaptic activity and participating in the occurrence and development of neurological diseases. The hydrolysates may have different physiological functions from the whole protein, and play different functions in neural activities, such as regulating synaptic plasticity, increasing synaptic strength and number, affecting amyloid-β polymerization, promoting glioma proliferation and growth, activating related signaling pathways, and so on. In this article, on the basis of elaborating the structure and function of neuroligin as a whole protein, the conditions and products of its hydrolysis are summarized and analyzed, and the functional consequences and physiological significance of its hydrolysis are discussed.

RETRACTED ARTICLE: Selected TLR7/8 agonist and type I interferon (IFN-α) cooperatively redefine the microglia transcriptome

Background

Microglia, the primary immune cells of the central nervous system, exerts multiple functions to mediate many neurological diseases. Upon any detection of invading pathogen products (e.g., TLR agonists) or host-released signaling factors (e.g., interferon/IFN), these cells undergo an activation process to release large numbers of inflammatory substances that participate in inflammation and homeostasis. The profound effects of inflammation associated with TLR7/8 agonist Resiquimod (R848) and type 1 interferon (e.g., IFN-α)-induced macrophage and dendritic cell activation on biological outcomes have long been recognized. However, the underlying mechanisms are not well defined in microglial cells.

Methods

The present study investigated the molecular signatures of microglia and identified genes that are uniquely or synergistically expressed in R848-, IFN-α- or R848 with IFN-α-treated primary microglial (PM) cells. We used RNA-sequencing, quantitative real-time PCR, and bioinformatics approaches to derive regulatory networks that control the transcriptional response of PM to R848, IFN-α and R848 with IFN-α.

Results

Our approach revealed that the inflammatory response in R848 with IFN-α-treated PM is faster and more intense than that in R848 or IFN-α-treated PM in terms of the number of differentially expressed genes and the magnitude of induction/repression. In particular, our integrative analysis enabled us to suggest the regulatory functions of TFs, which allowed the construction of a network model that explains how TLR7/8 and IFN-α-sensing pathways achieve specificity.

Conclusion

In conclusion, the systematic approach presented herein could be important to the understanding microglial activation-mediated molecular signatures induced by inflammatory stimuli related to TLR7/8, IFN-α or co-signaling, and associated transcriptional machinery of microglial functions and neuroinflammatory mechanisms.

Electronic supplementary material

The online version of this article (10.1007/s10787-019-00610-8) contains supplementary material, which is available to authorized users.

Increased matrix metalloproteinases in cerebrospinal fluids of patients with major depressive disorder and schizophrenia

BACKGROUND

Chronic inflammation of the brain has a pivotal role in the pathophysiology of major depressive disorder (MDD) and schizophrenia (SCZ). Matrix metalloproteinases (MMPs) are extracellular proteases involved in pro-inflammatory processes and interact with IL-6, which is increased in the cerebrospinal fluid (CSF) of patients with MDD and SCZ. However, MMPs in the CSF in patients with MDD and SCZ remains unclear. Therefore, we compared MMPs in the CSF of patients with MDD and SCZ to those of healthy controls (HC).

METHODS

Japanese patients were diagnosed with DSM-IV-TR and clinical symptoms were assessed with the Hamilton Rating Scale for Depression for MDD and the Positive and Negative Syndrome Scale for SCZ. CSF was obtained from MDD (n=90), SCZ (n=86) and from age- and sex-matched HC (n=106). The levels of MMPs in CSF were measured with multiplex bead-based immunoassay.

RESULTS

The levels of MMP-2 in CSF were higher in both MDD and SCZ than HC and were positively correlated with clinical symptomatic scores in MDD, but not in SCZ. Regardless of diagnosis, the levels of MMP-2, -7 and -10 were positively correlated with each other, and the levels of MMP-7 and -10 were higher in MDD, but not in SCZ, compared to HC.

CONCLUSION

Increased CSF levels of MMP-2 in MDD and SCZ may be associated with brain inflammation. State-dependent alteration of MMP-2 and activation of cascades involving MMP-2, -7, and -10 appeared to have a role in the pathophysiology of MDD.

Neutrophils: Underestimated Players in the Pathogenesis of Multiple Sclerosis (MS)

Neutrophils are the most abundant circulating and first-responding innate myeloid cells and have so far been underestimated in the context of multiple sclerosis (MS). MS is the most frequent, immune-mediated, inflammatory disease of the central nervous system. MS is treatable but not curable and its cause(s) and pathogenesis remain elusive. The involvement of neutrophils in MS pathogenesis has been suggested by the use of preclinical animal disease models, as well as on the basis of patient sample analysis. In this review, we provide an overview of the possible mechanisms and functions by which neutrophils may contribute to the development and pathology of MS. Neutrophils display a broad variety of effector functions enabling disease pathogenesis, including (1) the release of inflammatory mediators and enzymes, such as interleukin-1β, myeloperoxidase and various proteinases, (2) destruction and phagocytosis of myelin (as debris), (3) release of neutrophil extracellular traps, (4) production of reactive oxygen species, (5) breakdown of the blood-brain barrier and (6) generation and presentation of autoantigens. An important question relates to the issue of whether neutrophils exhibit a predominantly proinflammatory function or are also implicated in the resolution of chronic inflammatory responses in MS.