Chronic expression of monocyte chemoattractant protein-1 in the central nervous system causes delayed encephalopathy and impaired microglial function in mice

Multiple sclerosis: role of meningeal lymphoid aggregates in progression independent of relapse activity

The emphasis on mechanisms driving multiple sclerosis (MS) symptomatic worsening suggests that we move beyond categorical clinical classifiers such as relapsing-remitting MS (RR-MS) and progressive MS (P-MS). Here, we focus on the clinical phenomenon progression independent of relapse activity (PIRA), which begins early in the disease course. PIRA occurs throughout MS, becoming more phenotypically evident as patients age. The underlying mechanisms for PIRA include chronic-active demyelinating lesions (CALs), subpial cortical demyelination, and nerve fiber injury following demyelination. We propose that much of the tissue injury associated with PIRA is driven by autonomous meningeal lymphoid aggregates, present before disease onset and unresponsive to current therapeutics. Recently, specialized magnetic resonance imaging (MRI) has identified and characterized CALs as paramagnetic rim lesions in humans, enabling novel radiographic-biomarker-clinical correlations to further understand and treat PIRA.

Angiotensin-converting enzyme 2: a key enzyme in key organs

2020 marked the 20th anniversary of the discovery of the angiotensin-converting enzyme 2 (ACE2). This major event that changed the way we see the renin-angiotensin system today could have passed quietly. Instead, the discovery that ACE2 is a major player in the severe acute respiratory syndrome coronavirus 2 pandemic has blown up the literature regarding this enzyme. ACE2 connects the classical arm renin-angiotensin system, consisting mainly of angiotensin II peptide and its AT1 receptor, with a protective arm, consisting mainly of the angiotensin 1-7 peptide and its Mas receptor. In this brief article, we have reviewed the literature to describe how ACE2 is a key protective arm enzyme in the function of many organs, particularly in the context of brain and cardiovascular function, as well as in renal, pulmonary and digestive homeostasis. We also very briefly review and refer to recent literature to present an insight into the role of ACE2 in determining the course of coronavirus diseases 2019.

Association between plasma monocyte trafficking-related molecules and future risk of depression in older adults

BACKGROUND

The recruitment of monocytes to the brain plays an important role in the development of depression. However, the association between plasma biomarkers of monocyte trafficking and depression is unclear. This study is aimed to examine the effects of plasma monocyte chemoattractant protein-1 (MCP-1), intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) on the risk of depression.

METHODS

Data were acquired from an ongoing prospective cohort study involving randomly sampled, community-dwelling Korean older adults, which has been followed every two years. We included 1,539 euthymic older adults (age = 68.2 [5.6] years; 51.7% were women) without a history of major psychiatric disorders, and dementia and neurological diseases. Geriatric psychiatrists diagnosed incident depression through a structured interview using the Korean version of the Mini International Neuropsychiatric Interview.

RESULTS

Depression had developed in 134 (8.7 %) participants during the follow-up period of 5.7 (0.8) years. The high plasma MCP-1 tertile group showed two-fold higher risk of depression than the low plasma MCP-1 tertile group (hazards ratio [HR] = 2.00, 95% confidence intervals [CI] = 1.27 - 3.13, p = 0.003). The association between high levels of plasma MCP-1 and future risk of depression was significant in the middle plasma ICAM-1 and VCAM-1 tertile groups; the high plasma MCP-1 tertile group showed about four-fold higher risk of depression than the low plasma MCP-1 tertile group.

CONCLUSIONS

Molecules involved in monocyte trafficking may be good candidates as diagnostic biomarkers and/or therapeutic targets for late life depression.

Angiotensin-Converting Enzyme 2: SARS-CoV-2 Receptor and Regulator of the Renin-Angiotensin System: Celebrating the 20th Anniversary of the Discovery of ACE2

ACE2 (angiotensin-converting enzyme 2) has a multiplicity of physiological roles that revolve around its trivalent function: a negative regulator of the renin-angiotensin system, facilitator of amino acid transport, and the severe acute respiratory syndrome-coronavirus (SARS-CoV) and SARS-CoV-2 receptor. ACE2 is widely expressed, including, in the lungs, cardiovascular system, gut, kidneys, central nervous system, and adipose tissue. ACE2 has recently been identified as the SARS-CoV-2 receptor, the infective agent responsible for coronavirus disease 2019, providing a critical link between immunity, inflammation, ACE2, and cardiovascular disease. Although sharing a close evolutionary relationship with SARS-CoV, the receptor-binding domain of SARS-CoV-2 differs in several key amino acid residues, allowing for stronger binding affinity with the human ACE2 receptor, which may account for the greater pathogenicity of SARS-CoV-2. The loss of ACE2 function following binding by SARS-CoV-2 is driven by endocytosis and activation of proteolytic cleavage and processing. The ACE2 system is a critical protective pathway against heart failure with reduced and preserved ejection fraction including, myocardial infarction and hypertension, and against lung disease and diabetes mellitus. The control of gut dysbiosis and vascular permeability by ACE2 has emerged as an essential mechanism of pulmonary hypertension and diabetic cardiovascular complications. Recombinant ACE2, gene-delivery of Ace2, Ang 1-7 analogs, and Mas receptor agonists enhance ACE2 action and serve as potential therapies for disease conditions associated with an activated renin-angiotensin system. rhACE2 (recombinant human ACE2) has completed clinical trials and efficiently lowered or increased plasma angiotensin II and angiotensin 1-7 levels, respectively. Our review summarizes the progress over the past 20 years, highlighting the critical role of ACE2 as the novel SARS-CoV-2 receptor and as the negative regulator of the renin-angiotensin system, together with implications for the coronavirus disease 2019 pandemic and associated cardiovascular diseases.

Role of MCP-1 and CCR2 in ethanol-induced neuroinflammation and neurodegeneration in the developing brain

Background

Neuroinflammation and microglial activation have been implicated in both alcohol use disorders (AUD) and fetal alcohol spectrum disorders (FASD). Chemokine monocyte chemoattractant protein 1 (MCP-1) and its receptor C-C chemokine receptor type 2 (CCR2) are critical mediators of neuroinflammation and microglial activation. FASD is the leading cause of mental retardation, and one of the most devastating outcomes of FASD is the loss of neurons in the central nervous system (CNS). The underlying molecular mechanisms, however, remain unclear. We hypothesize that MCP-1/CCR2 signaling mediates ethanol-induced neuroinflammation and microglial activation, which exacerbates neurodegeneration in the developing brain.

Methods

C57BL/6 mice and mice deficient of MCP-1 (MCP-1^−/−) and CCR2 (CCR2^−/−) were exposed to ethanol on postnatal day 4 (PD4). Neuroinflammation, and microglial activation, and neurodegeneration in the brain were evaluated by immunohistochemistry and immunoblotting. A neuronal and microglial co-culture system was used to evaluate the role of microglia and MCP-1/CCR2 signaling in ethanol-induced neurodegeneration. Specific inhibitors were employed to delineate the involved signaling pathways.

Results

Ethanol-induced microglial activation, neuroinflammation, and a drastic increase in the mRNA and protein levels of MCP-1. Treatment of Bindarit (MCP-1 synthesis inhibitor) and RS504393 (CCR2 antagonist) significantly reduced ethanol-induced microglia activation/neuroinflammation, and neuroapoptosis in the developing brain. MCP-1^−/− and CCR2^−/− mice were more resistant to ethanol-induced neuroapoptosis. Moreover, ethanol plus MCP-1 caused more neuronal death in a neuron/microglia co-culture system than neuronal culture alone, and Bindarit and RS504393 attenuated ethanol-induced neuronal death in the co-culture system. Ethanol activated TLR4 and GSK3β, two key mediators of microglial activation in the brain and cultured microglial cells (SIM-A9). Blocking MCP-1/CCR2 signaling attenuated ethanol-induced activation of TLR4 and GSK3β.

Conclusion

MCP-1/CCR2 signaling played an important role in ethanol-induced microglial activation/neuroinflammation and neurodegeneration in the developing brain. The effects may be mediated by the interaction among MCP-1/CCR2 signaling, TLR4, and GSK3β.

Analysis of monocyte infiltration in MPTP mice reveals that microglial CX3CR1 protects against neurotoxic over-induction of monocyte-attracting CCL2 by astrocytes

Background

Evidence from mice suggests that brain infiltrating immune cells contribute to neurodegeneration, and we previously identified a deleterious lymphocyte infiltration in Parkinson’s disease mice. However, this remains controversial for monocytes, due to artifact-prone techniques used to distinguish them from microglia. Our aim was to reassess this open question, by taking advantage of the recent recognition that chemokine receptors CCR2 and CX3CR1 can differentiate between inflammatory monocytes and microglia, enabling to test whether CCR2⁺ monocytes infiltrate the brain during dopaminergic (DA) neurodegeneration and whether they contribute to neuronal death. This revealed unexpected insights into possible regulation of monocyte-attracting CCL2 induction.

Methods

We used acute 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mice and assessed monocyte infiltration by combining laser microdissection-guided chemokine RNA profiling of the substantia nigra (SN) with immunohistochemistry and CCR2-GFP reporter mice. To determine contribution to neuronal loss, we used CCR2-deletion and CCL2-overexpression, to reduce and increase CCR2⁺ monocyte infiltration, and CX3CR1-deletion to assess a potential implication in CCL2 regulation.

Results

Nigral chemokine profiling revealed early CCL2/7/12-CCR2 axis induction, suggesting monocyte infiltration in MPTP mice. CCL2 protein showed early peak induction in nigral astrocytes, while CCR2-GFP mice revealed early but limited nigral monocyte infiltration. However, blocking infiltration by CCR2 deletion did not influence DA neuronal loss. In contrast, transgenic astrocytic CCL2 over-induction increased CCR2⁺ monocyte infiltration and DA neuronal loss in MPTP mice. Surprisingly, CCL2 over-induction was also detected in MPTP intoxicated CX3CR1-deleted mice, which are known to present increased DA neuronal loss. Importantly, CX3CR1/CCL2 double-deletion suggested that increased neurotoxicity was driven by astrocytic CCL2 over-induction.

Conclusions

We show that CCR2⁺ monocytes infiltrate the affected CNS, but at the level observed in acute MPTP mice, this does not contribute to DA neuronal loss. In contrast, the underlying astrocytic CCL2 induction seemed to be tightly controled, as already moderate CCL2 over-induction led to increased neurotoxicity in MPTP mice, likely due to the increased CCR2⁺ monocyte infiltration. Importantly, we found evidence suggesting that during DA neurodegeneration, this control was mediated by microglial CX3CR1 signaling, which protects against such neurotoxic CCL2 over-induction by astrocytes, thus hinting at an endogenous mechanism to limit neurotoxic effects of the CCL2-CCR2 axis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-017-0830-9) contains supplementary material, which is available to authorized users.

Degradability and Clearance of Silicon, Organosilica, Silsesquioxane, Silica Mixed Oxide, and Mesoporous Silica Nanoparticles

The biorelated degradability and clearance of siliceous nanomaterials have been questioned worldwide, since they are crucial prerequisites for the successful translation in clinics. Typically, the degradability and biocompatibility of mesoporous silica nanoparticles (MSNs) have been an ongoing discussion in research circles. The reason for such a concern is that approved pharmaceutical products must not accumulate in the human body, to prevent severe and unpredictable side-effects. Here, the biorelated degradability and clearance of silicon and silica nanoparticles (NPs) are comprehensively summarized. The influence of the size, morphology, surface area, pore size, and surface functional groups, to name a few, on the degradability of silicon and silica NPs is described. The noncovalent organic doping of silica and the covalent incorporation of either hydrolytically stable or redox- and enzymatically cleavable silsesquioxanes is then described for organosilica, bridged silsesquioxane (BS), and periodic mesoporous organosilica (PMO) NPs. Inorganically doped silica particles such as calcium-, iron-, manganese-, and zirconium-doped NPs, also have radically different hydrolytic stabilities. To conclude, the degradability and clearance timelines of various siliceous nanomaterials are compared and it is highlighted that researchers can select a specific nanomaterial in this large family according to the targeted applications and the required clearance kinetics.

Clearance of cerebral Aβ in Alzheimer's disease: reassessing the role of microglia and monocytes

Deficiency in cerebral amyloid β-protein (Aβ) clearance is implicated in the pathogenesis of the common late-onset forms of Alzheimer’s disease (AD). Accumulation of misfolded Aβ in the brain is believed to be a net result of imbalance between its production and removal. This in turn may trigger neuroinflammation, progressive synaptic loss, and ultimately cognitive decline. Clearance of cerebral Aβ is a complex process mediated by various systems and cell types, including vascular transport across the blood–brain barrier, glymphatic drainage, and engulfment and degradation by resident microglia and infiltrating innate immune cells. Recent studies have highlighted a new, unexpected role for peripheral monocytes and macrophages in restricting cerebral Aβ fibrils, and possibly soluble oligomers. In AD transgenic (ADtg) mice, monocyte ablation or inhibition of their migration into the brain exacerbated Aβ pathology, while blood enrichment with monocytes and their increased recruitment to plaque lesion sites greatly diminished Aβ burden. Profound neuroprotective effects in ADtg mice were further achieved through increased cerebral recruitment of myelomonocytes overexpressing Aβ-degrading enzymes. This review summarizes the literature on cellular and molecular mechanisms of cerebral Aβ clearance with an emphasis on the role of peripheral monocytes and macrophages in Aβ removal.

A pH-responsive sequential-disassembly nanohybrid for mitochondrial targeting

Cationic materials have been reported as promising tools for targeting to mitochondria which are the "power houses" and "metabolic garbage keepers" of cells. However, their positive nature also restricts their in vivo application due to the quick clearance. Herein, we fabricated a nanohybrid consisting of the pH-responsive N-(2-hydroxypropyl)methacrylamide (HPMA) co-polymer (R-P) shells and positive mesoporous silica nanoparticle cores via electrostatic interaction. The anticancer drug, docetaxel (DTX), was encapsulated in the positive MSN cores (MSN-DTX). Once concealed by the anionic R-P shield, the assembled nanohybrid R-P@MSN-DTX will achieve prolonged blood circulation thereby leading to an enhanced EPR effect. At mildly acidic tumor environmental pH, first-stage charge reversion took place due to the hydrolysis of the amide bond on HPMA co-polymers. The de-attachment of the HPMA co-polymer occurred because of the positive charge repulsion and partial exposure of the positively charged MSN core promoted the cell internalization. The second-stage pH-responsiveness in the endo/lysosomes with a more acidic environment accelerates the disassembly of the nanohybrid and the leakage of the core facilitated the endo/lysosome escape and mitochondrial targeting with the help of intracellular compartmental acidity. Gathering up the characteristics of neutralized charge and stepwise pH-responsiveness, the R-P@MSN-DTX acquired a good tumor inhibition rate of 72.6% on nude mice. Our report provided a reference for systemic mitochondrial targeting achieved by the union of "assembly-disassembly".

Combination of butylphthalide with umbilical mesenchymal stem cells for the treatment of delayed encephalopathy after carbon monoxide poisoning

Delayed encephalopathy after carbon monoxide (CO) poisoning (DEACMP) is still a clinical challenge. This study aimed to investigate the efficacy of combined therapy of mesenchymal stem cell (MSC) transplantation and butylphthalide in DEACMP patients.Forty-two DEACMP patients were treated with 1 of the 3 therapies: combined therapy of MSC transplantation and butylphthalide; MSC transplantation alone; or hyperbaric oxygen therapy. The MSCs were alternatively injected into the subarachnoid space and the carotid artery using a self-made high-pressure injector. The Mini-Mental State Examination and the Barthel index of activities of daily living were administered before the treatment, and at 1 month, 3 months, and 6 months after the treatment. Computed tomography and magnetic resonance imaging results before and after the treatment were compared.At 1 month, 3 months, and 6 months after the treatment, the Mini-Mental State Examination scores and the Barthl scores were significantly higher in patients with the combined therapy of MSC transplantation and butylphthalide than those in patients with MSC transplantation alone or hyperbaric oxygen therapy (all P < 0.0001). No significant adverse events occurred.The combination of MSC transplantation and butylphthalide is safe and effective in treating DEACMP.

Impact of Increased Astrocyte Expression of IL-6, CCL2 or CXCL10 in Transgenic Mice on Hippocampal Synaptic Function

An important aspect of CNS disease and injury is the elevated expression of neuroimmune factors. These factors are thought to contribute to processes ranging from recovery and repair to pathology. The complexity of the CNS and the multitude of neuroimmune factors that are expressed in the CNS during disease and injury is a challenge to an understanding of the consequences of the elevated expression relative to CNS function. One approach to address this issue is the use of transgenic mice that express elevated levels of a specific neuroimmune factor in the CNS by a cell type that normally produces it. This approach can provide basic information about the actions of specific neuroimmune factors and can contribute to an understanding of more complex conditions when multiple neuroimmune factors are expressed. This review summarizes studies using transgenic mice that express elevated levels of IL-6, CCL2 or CXCL10 through increased astrocyte expression. The studies focus on the effects of these neuroimmune factors on synaptic function at the Schaffer collateral to CA1 pyramidal neuron synapse of the hippocampus, a brain region that plays a key role in cognitive function.

Eu/Tb codoped spindle-shaped fluorinated hydroxyapatite nanoparticles for dual-color cell imaging

Lanthanide doped fluorinated hydroxyapatite (FAp) nanoparticles are promising cell imaging nanomaterials but they are excited at wavelengths which do not match the light sources usually found in a commercial confocal laser scanning microscope (CLSM). In this work, we have successfully prepared spindle-shaped Eu/Tb codoped FAp nanoparticles by a hydrothermal method. Compared with single Eu doped FAp, Eu/Tb codoped FAp can be excited by a 488 nm laser, and exhibit both green and red light emission. By changing the amounts of Eu and Tb peaks, the emission in the green region (500-580 nm) can be decreased to the benefit of the emission in the red region (580-720 nm), thus reaching a balanced dual color emission. Using MC3T3-E1 cells co-cultured with Eu/Tb codoped FAp nanoparticles, it is observed that the nanoparticles are cytocompatible even at a concentration as high as 800 μg ml(-1). The Eu/Tb codoped FAp nanoparticles are located in the cytoplasm and can be monitored by dual color-green and red imaging with a single excitation light at 488 nm. At a concentration of 200 μg ml(-1), the cytoplasm is saturated in 8 hours, and Eu/Tb codoped FAp nanoparticles retain their fluorescence for at least 3 days. The cytocompatible Eu/Tb codoped FAp nanoparticles with unique dual color emission will be of great use for cell and tissue imaging.

C. elegans flavin-containing monooxygenase-4 is essential for osmoregulation in hypotonic stress

Studies in Caenorhabditis elegans have revealed osmoregulatory systems engaged when worms experience hypertonic conditions, but less is known about measures employed when faced with hypotonic stress. Inactivation of fmo-4, which encodes flavin-containing monooxygenase-4, results in dramatic hypoosmotic hypersensitivity; worms are unable to prevent overwhelming water influx and swell rapidly, finally rupturing due to high internal hydrostatic pressure. fmo-4 is expressed prominently in hypodermis, duct and pore cells but is excluded from the excretory cell. Thus, FMO-4 plays a crucial osmoregulatory role by promoting clearance of excess water that enters during hypotonicity, perhaps by synthesizing an osmolyte that acts to establish an osmotic gradient from excretory cell to duct and pore cells. C. elegans FMO-4 contains a C-terminal extension conserved in all nematode FMO-4s. The coincidently numbered human FMO4 also contains an extended C-terminus with features similar to those of FMO-4. Although these shared sequence characteristics suggest potential orthology, human FMO4 was unable to rescue the fmo-4 osmoregulatory defect. Intriguingly, however, mammalian FMO4 is expressed predominantly in the kidney - an appropriate site if it too is, or once was, involved in osmoregulation.

Bioactive SiO2@Ru nanoparticles for osteogenic differentiation of mesenchymal stem cells via activation of Akt signaling pathways

The surface chemistry of materials has an interactive influence on cell behavior.

Dual release of a hydrophilic and a hydrophobic osteogenic factor from a single liposome

Dual release of growth/differentiation factors from liposomes induced osteogenic differentiation of mesenchymal stem cells.

Shape matters when engineering mesoporous silica-based nanomedicines

This review introduces various fabrication methods for non-spherical mesoporous silica nanomaterials and the roles of particle shape in nanomedicine applications.

Silica-based matrices: State of the art and new perspectives for therapeutic drug delivery

Colloidal carriers based on silica (Si) matrices are an innovative approach within the context of therapeutic drug delivery systems. These carriers are emerging as a great promise for diagnosis and treatment of a wide range of injuries, particularly in cancer and infectious diseases. In addition, bioencapsulation for biosensing and cell therapy in silica sol-gel allows the survival of enzymes and cells for a long period of time. Owing to their porosity, large surface area, and high capability of functionalization, silica nanoparticles (SiNP) have been considered as an attractive option for several bioanalysis applications, such as selective bioseparation, imaging, and drug and gene delivery. However, although great advances are achieved in the biomedical fields, some toxicity effects can be associated with the use of SiNP. This article aims to present a comprehensive review of recent technological advances for silica matrices in biomedical applications, as well as the potential impact of silica-based materials on human health and environment.

In vivo studies of nanostructure-based photosensitizers for photodynamic cancer therapy

Animal models, particularly rodents, are major translational models for evaluating novel anticancer therapeutics. In this review, different types of nanostructure-based photosensitizers that have advanced into the in vivo evaluation stage for the photodynamic therapy (PDT) of cancer are described. This article focuses on the in vivo efficacies of the nanostructures as delivery agents and as energy transducers for photosensitizers in animal models. These materials are useful in overcoming solubility issues, lack of tumor specificity, and access to tumors deep in healthy tissue. At the end of this article, the opportunities made possible by these multiplexed nanostructure-based systems are summarized, as well as the considerable challenges associated with obtaining regulatory approval for such materials. The following questions are also addressed: (1) Is there a pressing demand for more nanoparticle materials? (2) What is the prognosis for regulatory approval of nanoparticles to be used in the clinic?

A Multilayered Cell Culture Model for Transport Study in Solid Tumors: Evaluation of Tissue Penetration of Polyethyleneimine Based Cationic Micelles

Limited drug distribution is partially responsible for the efficacy gap between preclinical and clinical studies of nano-sized drug carriers for cancer therapy. In this study, we examined the transport behavior of cationic micelles formed from a triblock copolymer of poly(D,L-lactide-co-glycolide)-block-branched polyethyleneimine-block-poly(D,L-lactide-co-glycolide) using a unique in vitro tumor model composed of a multilayered cell culture (MCC) and an Ussing chamber system. The Cy3-labeled cationic micelles showed remarkable Cy3 distribution in the MCC whereas charge-shielded micelles with a poly(ethylene glycol) surface accumulated on the surface of the MCC. Penetration occurred against convectional flow caused by a hydraulic pressure gradient. The study using fluorescence resonance energy transfer (FRET) showed that the cationic micelles dissociate at the interface between the culture media and the MCC or possibly inside of the first-layer cells and penetrates into the MCC as unimers. The penetration and distribution were energy-dependent and suppressed by various endocytic inhibitors. These suggest that cationic unimers mainly utilized clathrin-mediated endocytosis and macropinocytosis for cellular entry and a significant fraction were exocytosed by an unknown mechanism.

Synergistic antiproliferative effects of methotrexate-loaded smart silica nanocomposites in MDA-MB-231 breast cancer cells

In this study, the ability of methotrexate (MTX)-loaded stimuli-responsive novel silica nanocomposites (MSNs) (with mean diameter of ± 60 nm) in the induction of apoptosis, and change in the Bax/Bcl-2 mRNA levels, were investigated. MTT assay and RT -PCR analysis were performed on MDA-MB-231 breast cancer cells, to evaluate their anti-proliferative, apoptotic and anti-apoptotic effects. MTX-loaded MSNs caused marked decrease in the percentage of viable cells, with a significant down-regulation in the level of expression of the anti-apoptotic gene (Bcl-2), and up-regulation in the apoptotic gene (Bax). MTX-loaded MSNs increased the efficacy of the chemotherapeutic agents in the inhibition of cell proliferation and induction of apoptosis.

An in situ synthesis of mesoporous SBA-16/hydroxyapatite for ciprofloxacin release: in vitro stability and cytocompatibility studies

The present work developed a biomaterial (HA/SBA-16) based on the growth of calcium phosphate (HA) particles within an organized silica structure (SBA-16) to evaluate its application as a drug delivery system. The samples were charged with ciprofloxacin as a model drug and in vitro release assays were carried out. The samples were characterized by elemental analysis (CHN), Fourier transform infrared spectroscopy, nitrogen adsorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), small angle X-ray scattering (SAXS) and X-ray diffraction. The results obtained by TEM, SEM and SAXS reveal a well-defined cubic arrangement of a uniform spherical mesoporous structure, an intrinsic characteristic of these materials, which indicated that SBA-16 and HA/SBA-16 could potentially encapsulate bioactive molecules by means of ordered mesopores. It was found that both surface interaction and pore volume affect the rate and amount of ciprofloxacin released from the mesoporous materials. In vitro assays were performed to evaluate the adhesion, viability, and growth behavior of human adipose tissue-derived stem cells (hADSC) on SBA-16 and HA/SBA-16 nanocomposites to verify their potential as a scaffold for application in bone-tissue engineering using MTT assay and alkaline phosphatase activity tests. The results showed that the materials are promising systems for bone repair, providing a good environment for the adhesion and proliferation of rat mesenchymal stem cells and hADSC in vitro.

Microglial pathology

This paper summarizes pathological changes that affect microglial cells in the human brain during aging and in aging-related neurodegenerative diseases, primarily Alzheimer’s disease (AD). It also provides examples of microglial changes that have been observed in laboratory animals during aging and in some experimentally induced lesions and disease models. Dissimilarities and similarities between humans and rodents are discussed in an attempt to generate a current understanding of microglial pathology and its significance during aging and in the pathogenesis of Alzheimer dementia (AD). The identification of dystrophic (senescent) microglia has created an ostensible conflict with prior work claiming a role for activated microglia and neuroinflammation during normal aging and in AD, and this has raised a basic question: does the brain’s immune system become hyperactive (inflamed) or does it become weakened (senescent) in elderly and demented people, and what is the impact on neuronal function and cognition? Here we strive to reconcile these seemingly contradictory notions by arguing that both low-grade neuroinflammation and microglial senescence are the result of aging-associated free radical injury. Both processes are damaging for microglia as they synergistically exhaust this essential cell population to the point where the brain’s immune system is effete and unable to support neuronal function.

Selective elevation of circulating CCL2/MCP1 levels in patients with longstanding post-vaccinal macrophagic myofasciitis and ASIA

Several medical conditions sharing similar signs and symptoms may be related to immune adjuvants. These conditions described as ASIA (Autoimmune/inflammatory Syndrome Induced by Adjuvants), include a condition characterized by macrophagic myofasciitis (MMF) assessing long-term persistence of vaccine derived-alum adjuvants into macrophages at sites of previous immunization. Despite increasing data describing clinical manifestations of ASIA have been reported, biological markers are particularly lacking for their characterization and follow up. We report an extensive cytokine screening performed in serum from 44 MMF patients compared both to sex and age matched healthy controls and to patients with various types of inflammatory neuromuscular diseases. Thirty cytokines were quantified using combination of Luminex® technology and ELISA. There was significant mean increase of serum levels of the monocytechemoattractant protein 1 (CCL2/MCP-1) in MMF patients compared to healthy subjects. MMF patients showed no elevation of other cytokines. This contrasted with inflammatory patients in whom CCL2/MCP-1 serum levels were unchanged, whereas several other inflammatory cytokines were elevated (IL1β, IL5 and CCL3/MIP1α). These results suggest that CCL2 may represent a biological marker relevant to the pathophysiology of MMF rather than a non specific inflammatory marker and that it should be checked in the other syndromes constitutive of ASIA.

SCM-198 inhibits microglial overactivation and attenuates Aβ(1-40)-induced cognitive impairments in rats via JNK and NF-кB pathways

BACKGROUND

Neuroinflammation mediated by overactivated microglia plays a key role in many neurodegenerative diseases, including Alzheimer's disease (AD). In this study, we investigated for the first time the anti-neuroinflammatory effects and possible mechanisms of SCM-198 (an alkaloid extracted from Herbaleonuri), which was previously found highly cardioprotective, both in vitro and in vivo.

METHODS

For in vitro experiments, lipopolysaccharide (LPS) or β-amyloid(1-40) (Aβ(1-40)) was applied to induce microglial overactivation. Proinflammatory mediators were measured and activations of NF-κB and mitogen-activated protein kinases' (MAPKs) pathways were investigated. Further protective effect of SCM-198 was evaluated in microglia-neuron co-culture assay and Sprague-Dawley (SD) rats intrahippocampally-injected with Aβ(1-40).

RESULTS

SCM-198 reduced expressions of nitric oxide (NO), TNF-α, IL-1β and IL-6 possibly via, at least partially, inhibiting c-Jun N-terminal kinase (JNK) and NF-κB signaling pathways in microglia. Co-culture assay showed that activated microglia pretreated with SCM-198 led to less neuron loss and decreased phosphorylation of tau and extracellular signal-regulated kinase (ERK) in neurons. Besides, SCM-198 also directly protected against Aβ(1-40)-induced neuronal death and lactate dehydrogenase (LDH) release in primary cortical neurons. For in vivo studies, SCM-198 significantly enhanced cognitive performances of rats 12 days after intrahippocampal injections of aged Aβ(1-40) peptides in the Morris water maze (MWM), accompanied by less hippocampal microglial activation, decreased synaptophysin loss and phosphorylation of ERK and tau. Co-administration of donepezil and SCM-198 resulted in a slight cognitive improvement in SD rats 50 days after intrahippocampal injections of aged Aβ(1-40) peptides as compared to only donepezil or SCM-198 treated group.

CONCLUSIONS

Our findings are the first to report that SCM-198 has considerable anti-neuroinflammatory effects on inhibiting microglial overactivation and might become a new potential drug candidate for AD therapy in the future.

Increased astrocyte expression of IL-6 or CCL2 in transgenic mice alters levels of hippocampal and cerebellar proteins

Emerging research has identified that neuroimmune factors are produced by cells of the central nervous system (CNS) and play critical roles as regulators of CNS function, directors of neurodevelopment and responders to pathological processes. A wide range of neuroimmune factors are produced by CNS cells, primarily the glial cells, but the role of specific neuroimmune factors and their glial cell sources in CNS biology and pathology have yet to be fully elucidated. We have used transgenic mice that express elevated levels of a specific neuroimmune factor, the cytokine IL-6 or the chemokine CCL2, through genetic modification of astrocyte expression to identify targets of astrocyte produced IL-6 or CCL2 at the protein level. We found that in non-transgenic mice constitutive expression of IL-6 and CCL2 occurs in the two CNS regions studied, the hippocampus and cerebellum, as measured by ELISA. In the CCL2 transgenic mice elevated levels of CCL2 were evident in the hippocampus and cerebellum, whereas in the IL-6 transgenic mice, elevated levels of IL-6 were only evident in the cerebellum. Western blot analysis of the cellular and synaptic proteins in the hippocampus and cerebellum of the transgenic mice showed that the elevated levels of CCL2 or IL-6 resulted in alterations in the levels of specific proteins and that these actions differed for the two neuroimmune factors and for the two brain regions. These results are consistent with cell specific profiles of action for IL-6 and CCL2, actions that may be an important aspect of their respective roles in CNS physiology and pathophysiology.

CNS inflammation and bone marrow neuropathy in type 1 diabetes

By using pseudorabies virus expressing green fluorescence protein, we found that efferent bone marrow-neural connections trace to sympathetic centers of the central nervous system in normal mice. However, this was markedly reduced in type 1 diabetes, suggesting a significant loss of bone marrow innervation. This loss of innervation was associated with a change in hematopoiesis toward generation of more monocytes and an altered diurnal release of monocytes in rodents and patients with type 1 diabetes. In the hypothalamus and granular insular cortex of mice with type 1 diabetes, bone marrow-derived microglia/macrophages were activated and found at a greater density than in controls. Infiltration of CD45(+)/CCR2(+)/GR-1(+)/Iba-1(+) bone marrow-derived monocytes into the hypothalamus could be mitigated by treatment with minocycline, an anti-inflammatory agent capable of crossing the blood-brain barrier. Our studies suggest that targeting central inflammation may facilitate management of microvascular complications.

Differential role of CCR2 in the dynamics of microglia and perivascular macrophages during prion disease

The expansion of the microglial population is one of the hallmarks of numerous brain disorders. The addition of circulating progenitors to the pool of brain macrophages can contribute to the progression of brain disease and needs to be precisely defined to better understand the evolution of the glial and inflammatory reactions in the brain. We have analyzed the degree of infiltration/recruitment of circulating monocytes to the microglial pool, in a prion disease model of chronic neurodegeneration. Our results indicate a minimal/absent level of CCR2-dependent recruitment of circulating monocytes, local proliferation of microglia is the main driving force maintaining the amplification of the population. A deficiency in CCR2, and thus the absence of recruitment of circulating monocytes, does not impact microglial dynamics, the inflammatory profile or the temporal behavioral course of prion disease. However, the lack of CCR2 has unexpected effects including the failure to recruit perivascular macrophages in diseased but not healthy CNS and a small reduction in microglia proliferation. These data define the composition of the CNS-resident macrophage populations in prion disease and will help to understand the dynamics of the CNS innate immune response during chronic neurodegeneration.

Monocyte chemoattractant protein-1 and the blood-brain barrier

The blood-brain barrier (BBB) is a dynamic structure that maintains the homeostasis of the brain and thus proper neurological functions. BBB compromise has been found in many pathological conditions, including neuroinflammation. Monocyte chemoattractant protein-1 (MCP1), a chemokine that is transiently and significantly up-regulated during inflammation, is able to disrupt the integrity of BBB and modulate the progression of various diseases, including excitotoxic injury and hemorrhage. In this review, we first introduce the biochemistry and biology of MCP1, and then summarize the effects of MCP1 on BBB integrity as well as individual BBB components.

Immobilization of bioactive factor-loaded liposomes on the surface of electrospun nanofibers targeting tissue engineering

Dexamethasone-loaded liposomes immobilized at the surface of electrospun polycaprolactone nanofiber meshes successfully promoted the osteogenic differentiation of human bone marrow-derived mesenchymal stem cells.

Hyaluronic acid/poly-l-lysine bilayered silica nanoparticles enhance the osteogenic differentiation of human mesenchymal stem cells

The coating of silica nanoparticles with a bilayer of poly-l-lysine and hyaluronic acid enhances the osteogenic differentiation of human bone marrow stem cells at low nanoparticle concentrations (25 μg mL⁻¹ and 12.5 μg mL⁻¹).

Volume labeling with Alexa Fluor dyes and surface functionalization of highly sensitive fluorescent silica (SiO2) nanoparticles

A new synthesis approach is described that allows the direct incorporation of fluorescent labels into the volume or body of SiO2 nanoparticles. In this process, fluorescent Alexa Fluor dyes with different emission wavelengths were covalently incorporated into the SiO2 nanoparticles during their formation by the hydrolysis of tetraethoxysilane. The dye molecules were homogeneously distributed throughout the SiO2 nanoparticles. The quantum yields of the Alexa Fluor volume-labeled SiO2 nanoparticles were much higher than nanoparticles labeled using conventional organic dyes. The size of the resulting nanoparticles was controlled using microemulsion reaction media with sizes in the range of 20-100 nm and a polydispersity of <15%. In comparison with conventional surface tagged particles created by post-synthesis modification, this process maintains the physical and surface chemical properties that have the most pronounced effect on colloidal stability and interactions with their surroundings. These volume-labeled nanoparticles have proven to be extremely robust, showing excellent signal strength, negligible photobleaching, and minimal loss of functional organic components. The native or "free" surface of the volume-labeled particles can be altered to achieve a specific surface functionality without altering fluorescence. Their utility was demonstrated for visualizing the association of surface-modified fluorescent particles with cultured macrophages. Differences in particle agglomeration and cell association were clearly associated with differences in observed nanoparticle toxicity. The capacity to maintain particle fluorescence while making significant changes to surface chemistry makes these particles extremely versatile and useful for studies of particle agglomeration, uptake, and transport in environmental and biological systems.

Diverse activation of microglia by chemokine (C-C motif) ligand 2 overexpression in brain

Background

The chemokine (C-C motif) ligand 2 (CCL2) is a monocyte chemoattractant protein that mediates macrophage recruitment and migration during peripheral and central nervous system (CNS) inflammation.

Methods

To determine the impact of CCL2 in inflammation in vivo and to elucidate the CCL2-induced polarization of activated brain microglia, we delivered CCL2 into the brains of wild-type mice via recombinant adeno-associated virus serotype 9 (rAAV-9) driven by the chicken β-actin promoter. We measured microglial activation using histological and chemical measurement and recruitment of monocytes using histology and flow cytometry.

Results

The overexpression of CCL2 in the CNS induced significant activation of brain resident microglia. CD45 and major histocompatibility complex class II immunoreactivity significantly increased at the sites of CCL2 administration. Histological characterization of the microglial phenotype revealed the elevation of “classically activated” microglial markers, such as calgranulin B and IL-1β, as well as markers associated with “alternative activation” of microglia, including YM1 and arginase 1. The protein expression profile in the hippocampus demonstrated markedly increased levels of IL-6, GM-CSF and eotaxin (CCL-11) in response to CCL2, but no changes in the levels of other cytokines, including TNF-α and IFN-γ. Moreover, real-time PCR analysis confirmed increases in mRNA levels of gene transcripts associated with neuroinflammation following CCL2 overexpression. Finally, we investigated the chemotactic properties of CCL2 in vivo by performing adoptive transfer of bone marrow–derived cells (BMDCs) isolated from donor mice that ubiquitously expressed green fluorescent protein. Flow cytometry and histological analyses indicated that BMDCs extravasated into brain parenchyma and colabeled with microglial markers.

Conclusion

Taken together, our results suggest that CCL2 strongly activates resident microglia in the brain. Both pro- and anti-inflammatory activation of microglia were prominent, with no bias toward the M1 or M2 phenotype in the activated cells. As expected, CCL2 overexpression actively recruited circulating monocytes into the CNS. Thus, CCL2 expression in mouse brain induces microglial activation and represents an efficient method for recruitment of peripheral macrophages.

Immune players in the CNS: the astrocyte

In the finely balanced environment of the central nervous system astrocytes, the most numerous cell type, play a role in regulating almost every physiological system. First found to regulate extracellular ions and pH, they have since been shown to regulate neurotransmitter levels, cerebral blood flow and energy metabolism. There is also growing evidence for an essential role of astrocytes in central immunity, which is the topic of this review. In the healthy state, the central nervous system is potently anti-inflammatory but under threat astrocytes readily respond to pathogens and to both sterile and pathogen-induced cell damage. In response, astrocytes take on some of the roles of immune cells, releasing cyto- and chemokines to influence effector cells, modulating the blood-brain barrier and forming glial scars. To date, much of the data supporting a role for astrocytes in immunity have been obtained from in vitro systems; however data from experimental models and clinical samples support the suggestion that astrocytes perform similar roles in more complex environments. This review will discuss some aspects of the role of astrocytes in central nervous system immunity.

Role of chemokine CCL2 and its receptor CCR2 in neurodegenerative diseases

Chemokines are members of the chemoattractant cytokine family. They play key roles in the trafficking of leukocytes and in the induction of chemotaxis through the activation of G protein-coupled receptor. Considerable interest has been paid to these molecules to elucidate their roles in the unique inflammatory responses elicited in the central nervous system (CNS). Chemokine CCL2 (also known as monocyte chemoattractant protein-1, MCP-1) is one of the vital chemokines that control the migration and infiltration of monocytes/macrophages. CCL2 and its receptor CCR2 have been shown to be induced and involved in various neurodegenerative disorders including Alzheimer's disease, multiple sclerosis, and ischemic brain injury. The present review will focus on the biological and pathophysiological aspects of CCL2 and CCR2 in the CNS and the possible therapeutic approaches for targeting these two proteins to combat neurodegenerative diseases.

High MRI performance fluorescent mesoporous silica-coated magnetic nanoparticles for tracking neural progenitor cells in an ischemic mouse model

Multifunctional probes with high MRI sensitivity and high efficiency for cell labeling are desirable for MR cell imaging. Herein, we have fabricated fluorescent mesoporous silica-coated superparamagnetic iron oxide nanoparticles (fmSiO4@SPIONs) for neural progenitor cell (C17.2) MR imaging. FmSiO4@SPIONs were discrete and uniform in size, and had a clear core-shell structure. The magnetic core size was about 10 nm and the fluorescent mesoporous silica coating layer was around 20 nm. Compared with fluorescent dense silica-coated SPIONs (fdSiO4@SPIONs) with a similar size, fmSiO4@SPIONs demonstrated higher MR sensitivity and cell labeling efficiency. When implanted into the right hemisphere of stroke mice, contralateral to the ischemic territory, a small amount of labeled cells were able to be tracked migrating to the lesion sites using a clinical MRI scanner (3 T). More impressively, even when administered intravenously, the labeled cells could also be monitored homing to the ischemic area. MRI observations were corroborated by histological studies of the brain tissues. Our study demonstrated that fmSiO4@SPIONs are highly effective for cell imaging and hold great promise for MRI cell tracking in future.

Involvement of lysosomal exocytosis in the excretion of mesoporous silica nanoparticles and enhancement of the drug delivery effect by exocytosis inhibition

The exocytosis of phosphonate modified mesoporous silica nanoparticles (P-MSNs) is demonstrated and lysosomal exocytosis is identified as the mechanism responsible for this event. Regulation of P-MSN exocytosis can be achieved by inhibiting or accelerating lysosomal exocytosis. Slowing down P-MSN exocytosis enhances the drug delivery effect of CPT-loaded P-MSNs by improving cell killing.

Systemic immune system alterations in early stages of Alzheimer's disease

Immune activation and inflammation play significant roles in the pathogenesis of Alzheimer's disease (AD). To test whether AD patients showed systemic manifestations of inflammation, blood from 41 patients with early stages of AD and 31 aged-match elderly controls were evaluated. Cellular markers for monocyte/macrophage (MO) activation and CD8 T lymphocyte were increased in early AD patients. Expression of monocyte CCR2, the receptor for monocyte chemoattractant protein-1 (MCP-1), was decreased; however, plasma MCP-1 levels were significantly increased and were related to the degree of MO activation in AD. These findings suggest that AD pathogenesis may be influenced by systemic immunologic dysfunction and provides potential immunologic targets for therapeutic intervention.

Synaptic plasticity in the hippocampus shows resistance to acute ethanol exposure in transgenic mice with astrocyte-targeted enhanced CCL2 expression

It has been shown that ethanol exposure can activate astrocytes and microglia resulting in the production of neuroimmune factors, including the chemokine CCL2. The role of these neuroimmune factors in the effects of ethanol on the central nervous system has yet to be elucidated. To address this question, we investigated the effects of ethanol on synaptic transmission and plasticity in the hippocampus from mice that express elevated levels of CCL2 in the brain and their non-transgenic littermate controls. The brains of the transgenic mice simulate one aspect of the alcoholic brain, chronically increased levels of CCL2. We used extracellular field potential recordings in acutely isolated hippocampal slices to identify neuroadaptive changes produced by elevated levels of CCL2 and how these neuroadaptive changes affect the actions of acute ethanol. Results showed that synaptic transmission and the effects of ethanol on synaptic transmission were similar in the CCL2-transgenic and non-transgenic hippocampus. However, long-term potentiation (LTP), a cellular mechanism thought to underlie learning and memory, in the CCL2-transgenic hippocampus was resistant to the ethanol-induced depression of LTP observed in the non-transgenic hippocampus. Consistent with these results, ethanol pretreatment significantly impaired cued and contextual fear conditioning in non-transgenic mice, but had no effect in CCL2-transgenic mice. These data show that chronically elevated levels of CCL2 in the hippocampus produce neuroadaptive changes that block the depressing effects of ethanol on hippocampal synaptic plasticity and support the hypothesis that CCL2 may provide a neuroprotective effect against the devastating actions of ethanol on hippocampal function.

Biofunctionalized quantum dots for live monitoring of stem cells: applications in regenerative medicine

AIM

This study aimed to live monitor the degree of endothelial progenitor cell (EPC) integration onto tissue-engineering scaffolds by conjugating relevant antibodies to quantum dots (QDs).

MATERIALS & METHODS

Biocompatible mercaptosuccinic acid-coated QDs were functionalized with two different antibodies to EPC (CD133 with QDs of 640 nm wavelength [λ] and later-stage mature EPCs; and von Willebrand factor with QDs of λ595 and λ555 nm) using conventional carbomide and N-hydroxysuccinimide chemistry. Biofunctionalization was characterized with Fourier-transform infrared spectroscopy. Cell viability assays and gross morphology observations confirmed cytocompatibility and normal patterns of celluar growth. The antigens corresponding to each state of cell maturation were determined using a single excitation at λ488 nm.

RESULTS

The optimal concentrations of antibody-QD conjugates were biocompatible, hemocompatible and determined the state of EPC transformation to endothelial cells.

CONCLUSION

Antibody-functionalized QDs suggest new applications in tissue engineering of polymer-based implants where cell integration can potentially be monitored without requiring the sacrifice of implants.