Phosphatidylserine and phosphatidylcholine-containing liposomes inhibit amyloid beta and interferon-gamma-induced microglial activation

Microglia and TREM2

TREM2 is a membrane receptor solely expressed on microglia in normal brain. In this review we outline recent advances in TREM2 biology and its implications for microglial function, with particular emphasis on findings from iPSC-derived microglia (iMG) expressing TREM2 loss-of-function mutations. Alterations in receptor proximal and distal signalling underlie TREM2 risk variants linked to neurodegenerative disease, principally NH-linked FTD, and late-onset AD, but emerging data suggest roles for TREM2 in PD, MS and ALS. TREM2 downstream functions include phagocytosis of myelin debris, amyloid beta peptides, and phosphatidylserine-expressing cells (resulting from damage or stress). Microglial survival, migration, DAMP signalling, inflammasome activation, and intercellular signalling including tau spreading via exosomes, as well as roles for sTREM2 in protection and as a biomarker are discussed. The role of TREM2 in metabolic homeostasis, and immunometabolic switching are discussed regarding microglial responses to damage and protection. The use of iPSC models to investigate the role of TREM2 in AD, PD, MS, ALS, and other neurodegenerative diseases could prove invaluable due to their ability to recapitulate human pathology, allowing a full understanding of TREM2 and microglial involvement in the underlying disease mechanisms and progression. This article is part of the Special Issue on "Microglia".

Hydrogel-based approaches to target hypersensitivity mechanisms underlying autoimmune disease

A robust adaptive immune response is essential for combatting pathogens. In the wrong context such as due to genetic and environmental factors, however, the same mechanisms crucial for self-preservation can lead to a loss of self-tolerance. Resulting autoimmunity manifests in the development of a host of organ-specific or systemic autoimmune diseases, hallmarked by aberrant immune responses and tissue damage. The prevalence of autoimmune diseases is on the rise, medical management of which focuses primarily on pharmacological immunosuppression that places patients at a risk of side effects, including opportunistic infections and tumorigenesis. Biomaterial-based drug delivery systems confer many opportunities to address challenges associated with conventional disease management. Hydrogels, in particular, can protect encapsulated cargo (drug or cell therapeutics) from the host environment, afford their presentation in a controlled manner, and can be tailored to respond to disease conditions or support treatment via multiplexed functionality. Moreover, localized delivery to affected sites by these approaches has the potential to concentrate drug action at the site, reduce off-target exposure, and enhance patient compliance by reducing the need for frequent administration. Despite their many benefits for the management of autoimmune disease, such biomaterial-based approaches focus largely on the downstream effects of hypersensitivity mechanisms and have a limited capacity to eradicate the disease. In contrast, direct targeting of mechanisms of hypersensitivity reactions uniquely enables prophylaxis or the arrest of disease progression by mitigating the basis of autoimmunity. One promising approach is to induce self-antigen-specific tolerance, which specifically subdues damaging autoreactivity while otherwise retaining the normal immune responses. In this review, we will discuss hydrogel-based systems for the treatment of autoimmune disease, with a focus on those that target hypersensitivity mechanisms head-on. As the field continues to advance, it will expand the range of therapeutic choices for people coping with autoimmune diseases, providing fresh prospects for better clinical outcomes and improved quality of life.

Biomaterials-based anti-inflammatory treatment strategies for Alzheimer's disease

The current therapeutic drugs for Alzheimer's disease only improve symptoms, they do not delay disease progression. Therefore, there is an urgent need for new effective drugs. The underlying pathogenic factors of Alzheimer's disease are not clear, but neuroinflammation can link various hypotheses of Alzheimer's disease; hence, targeting neuroinflammation may be a new hope for Alzheimer's disease treatment. Inhibiting inflammation can restore neuronal function, promote neuroregeneration, reduce the pathological burden of Alzheimer's disease, and improve or even reverse symptoms of Alzheimer's disease. This review focuses on the relationship between inflammation and various pathological hypotheses of Alzheimer's disease; reports the mechanisms and characteristics of small-molecule drugs (e.g., nonsteroidal anti-inflammatory drugs, neurosteroids, and plant extracts); macromolecule drugs (e.g., peptides, proteins, and gene therapeutics); and nanocarriers (e.g., lipid-based nanoparticles, polymeric nanoparticles, nanoemulsions, and inorganic nanoparticles) in the treatment of Alzheimer's disease. The review also makes recommendations for the prospective development of anti-inflammatory strategies based on nanocarriers for the treatment of Alzheimer's disease.

Antioxidative Stress Metabolic Pathways in Moderately Active Individuals

Physical activity (PA) is known to have beneficial effects on health, primarily through its antioxidative stress properties. However, the specific metabolic pathways that underlie these effects are not fully understood. This study aimed to investigate the metabolic pathways that are involved in the protective effects of moderate PA in non-obese and healthy individuals. Data on 305 young, non-obese participants were obtained from the Qatar Biobank. The participants were classified as active or sedentary based on their self-reported PA levels. Plasma metabolomics data were collected and analyzed to identify differences in metabolic pathways between the two groups. The results showed that active participants had increased activation of antioxidative, stress-related pathways, including lysoplasmalogen, plasmalogen, phosphatidylcholine, vitamin A, and glutathione. Additionally, there were significant associations between glutathione metabolites and certain clinical traits, including bilirubin, uric acid, hemoglobin, and iron. This study provides new insights into the metabolic pathways that are involved in the protective effects of moderate PA in non-obese and healthy individuals. The findings may have implications for the development of new therapeutic strategies that target these pathways.

Neuro-nanotechnology: diagnostic and therapeutic nano-based strategies in applied neuroscience

Artificial, de-novo manufactured materials (with controlled nano-sized characteristics) have been progressively used by neuroscientists during the last several decades. The introduction of novel implantable bioelectronics interfaces that are better suited to their biological targets is one example of an innovation that has emerged as a result of advanced nanostructures and implantable bioelectronics interfaces, which has increased the potential of prostheses and neural interfaces. The unique physical-chemical properties of nanoparticles have also facilitated the development of novel imaging instruments for advanced laboratory systems, as well as intelligently manufactured scaffolds and microelectrodes and other technologies designed to increase our understanding of neural tissue processes. The incorporation of nanotechnology into physiology and cell biology enables the tailoring of molecular interactions. This involves unique interactions with neurons and glial cells in neuroscience. Technology solutions intended to effectively interact with neuronal cells, improved molecular-based diagnostic techniques, biomaterials and hybridized compounds utilized for neural regeneration, neuroprotection, and targeted delivery of medicines as well as small chemicals across the blood-brain barrier are all purposes of the present article.

Strategies for Treatment of Disease-Associated Dementia Beyond Alzheimer's Disease: An Update

Memory, cognition, dementia, and neurodegeneration are complexly interlinked processes with various mechanistic pathways, leading to a range of clinical outcomes. They are strongly associated with pathological conditions like Alzheimer's disease, Parkinson's disease, schizophrenia, and stroke and are a growing concern for their timely diagnosis and management. Several cognitionenhancing interventions for management include non-pharmacological interventions like diet, exercise, and physical activity, while pharmacological interventions include medicinal agents, herbal agents, and nutritional supplements. This review critically analyzed and discussed the currently available agents under different drug development phases designed to target the molecular targets, including cholinergic receptor, glutamatergic system, GABAergic targets, glycine site, serotonergic targets, histamine receptors, etc. Understanding memory formation and pathways involved therein aids in opening the new gateways to treating cognitive disorders. However, clinical studies suggest that there is still a dearth of knowledge about the pathological mechanism involved in neurological conditions, making the dropouts of agents from the initial phases of the clinical trial. Hence, a better understanding of the disease biology, mode of drug action, and interlinked mechanistic pathways at a molecular level is required.

Liposome delivery to the brain with rapid short-pulses of focused ultrasound and microbubbles

Liposomes are clinically used drug carriers designed to improve the delivery of drugs to specific tissues while minimising systemic distribution. However, liposomes are unable to cross the blood-brain barrier (BBB) and enter the brain, mostly due to their large size (ca. 100 nm). A noninvasive and localised method of delivering liposomes across the BBB is to intravenously inject microbubbles and apply long pulses of ultrasound (pulse length: >1 ms) to a targeted brain region. Recently, we have shown that applying rapid short pulses (RaSP) (pulse length: 5 μs) can deliver drugs with an improved efficacy and safety profile. However, this was tested with a relatively smaller 3-kDa molecule (dextran). In this study, we examine whether RaSP can deliver liposomes to the murine brain in vivo. Fluorescent DiD-PEGylated liposomes were synthesized and injected intravenously alongside microbubbles. The left hippocampus of mice was then sonicated with either a RaSP sequence (5 μs at 1.25 kHz in groups of 10 ms at 0.5 Hz) or a long pulse sequence (10 ms at 0.5 Hz), with each pulse having a 1-MHz centre frequency (0.35 and 0.53 MPa). The delivery and distribution of the fluorescently-labelled liposomes were assessed by fluorescence imaging of the brain sections. The safety profile of the sonicated brains was assessed by histological staining. RaSP was shown to locally deliver liposomes across the BBB at 0.53 MPa with a more diffused and safer profile compared to the long pulse ultrasound sequence. Cellular uptake of liposomes was observed in neurons and microglia, while no uptake within astrocytes was observed in both RaSP and long pulse-treated brains. This study shows that RaSP allows a targeted and safe delivery of liposomal drugs into the murine brain with potential to deliver drugs into neuronal and glial targets.

Phospholipids (PLs) know-how: exploring and exploiting phospholipase D for its industrial dissemination

Owing to their numerous nutritional and bioactive functions, phospholipids (PLs), which are major components of biological membranes in all living organisms, have been widely applied as nutraceuticals, food supplements, and cosmetic ingredients. To date, PLs are extracted solely from soybean or egg yolk, despite the diverse market demands and high cost, owing to a tedious and inefficient manufacturing process. A microbial-based manufacturing process, specifically phospholipase D (PLD)-based biocatalysis and biotransformation process for PLs, has the potential to address several challenges associated with the soybean- or egg yolk-based supply chain. However, poor enzyme properties and inefficient microbial expression systems for PLD limit their wide industrial dissemination. Therefore, sourcing new enzyme variants with improved properties and developing advanced PLD expression systems are important. In the present review, we systematically summarize recent achievements and trends in the discovery, their structural properties, catalytic mechanisms, expression strategies for enhancing PLD production, and its multiple applications in the context of PLs. This review is expected to assist researchers to understand current advances in this field and provide insights for further molecular engineering efforts toward PLD-mediated bioprocessing.

A biocompatible and injectable hydrogel to boost the efficacy of stem cells in neurodegenerative diseases treatment

AIMS

Stem cell therapies emerged as treatment modalities with potential to cure neurodegenerative diseases (NDs). However, despite high expectations, their clinical use is still limited. Critical issues in treatment outcomes may be related to stem cells formulation and administration route. We develop a hydrogel as a cell carrier, consisting of compounds (phospholipids and hyaluronic acid-HA) naturally present in the central nervous system (CNS). The HA-based hydrogel physically crosslinked with liposomes is designed for direct injection into the CNS to significantly increase the bone marrow mesenchymal stem cells (BMSCs) bioavailability.

MATERIALS AND METHODS

Hydrogel compatibility is confirmed in vitro with BMSCs and in vivo through its intracerebroventricular injection in rats. To assess its efficacy, the main cause of chronic neurologic disability in young adults is selected, namely multiple sclerosis (MS). The efficacy of the developed formulation containing a lower number of cells than previously reported is demonstrated using an experimental autoimmune encephalomyelitis (EAE) rat model.

KEY FINDINGS

The distribution of the engineered hydrogel into corpus callosum can be ideal for NDs treatment, since damage of this white matter structure is responsible for important neuronal deficits. Moreover, the BMSCs-laden hydrogel significantly decreases disease severity and maximum clinical score and eliminated the relapse.

SIGNIFICANCE

The engineering of advanced therapies using this natural carrier can result in efficacious treatments for MS and related debilitating conditions.

Glutathione- and apolipoprotein E-grafted liposomes to regulate mitogen-activated protein kinases and rescue neurons in Alzheimer's disease

Neurodegenerative disorders, such as Alzheimer's disease (AD), present biomedical challenges due to inability of pharmaceuticals to permeate the blood-brain barrier (BBB) and lack of therapeutic specificity in definite sites against multiple pathologies. Phosphatidylcholine (PC)-liposomes carrying curcumin (CURC), quercetin (QU), epigallocatechin gallate (EGCG) and rosmarinic acid (RA) with crosslinked glutathione (GSH) and apolipoprotein E (ApoE) were fabricated to recognize brain microvascular endothelial cells and amyloid beta (Aβ), and reduce tau protein hyperphosphorylation for AD management. Addition of stearic acid to liposomal bilayers ameliorated particle stability, promoted drug entrapment efficiency, and prolonged drug release duration. The triple targeting liposomes boosted the capability of CURC, QU, EGCG and RA for crossing the BBB with the assistance of grafted GSH and ApoE and docking Aβ around SK-N-MC cells using ApoE and PC. Moreover, GSH-ApoE-PC-liposomes benefited the 4 medicines in simultaneously transporting to Aβ_1-42-insulted neurons, in functioning against hyperphosphorylated mitogen-activated protein kinases, including p-c-Jun N-terminal protein kinase, p-extracellular signal-regulated protein kinase 1/2 and p-p38, in downregulating tau protein at S202, caspase-3 and interleukin-6, and in upregulating p-cyclic adenosine monophosphate response element-binding protein. GSH-ApoE-PC-liposomes can be promising colloidal carriers in delivering CURC, QU, EGCG and RA to degenerated neural tissue in a controlled manner, targeting pathological factors for neuroprotection, and raising preclinical effectualness for AD treatment.

Neuroprotective phosphatidylserine liposomes alleviate depressive-like behavior related to stroke through neuroinflammation attenuation in the mouse hippocampus

OBJECTIVE

To investigate the protective effect of phosphatidylserine liposomes (PSL) on post-stroke (ST) injuries such as neuroinflammation and depression in mice.

METHODS

Brain ischemia was induced via the right unilateral common carotid artery occlusion model. Then, behavioral assessments including the forced swimming test (FST) and tail suspension test (TST) were used to evaluate the antidepressant-like effect of PSL. Moreover, inflammatory cytokines changes in the hippocampus including TNF-α and IL-10 levels as well as the number of survived neurons were evaluated in ST mice using immunohistochemistry (IHC).

RESULTS

A significant reduction of the immobility time in both behavioral tests indicated the antidepressant activity of PSL. Moreover, the number of viable neurons increased significantly with PSL treatment, which was similar to control group, compared to the untreated ST group. IHC analysis of ST mice receiving PSL showed a significant reduction in TNF-α and IL-10 levels in the inflamed hippocampus of mice.

CONCLUSION

Oral PSL may improve post-stroke depression (PSD) through its anti-inflammatory properties.

Strategies and Tools for Studying Microglial-Mediated Synapse Elimination and Refinement

The role of microglia in controlling synapse homeostasis is becoming increasingly recognized by the scientific community. In particular, the microglia-mediated elimination of supernumerary synapses during development lays the basis for the correct formation of neuronal circuits in adulthood, while the possible reactivation of this process in pathological conditions, such as schizophrenia or Alzheimer's Disease, provides a promising target for future therapeutic strategies. The methodological approaches to investigate microglial synaptic engulfment include different in vitro and in vivo settings. Basic in vitro assays, employing isolated microglia and microbeads, apoptotic membranes, liposomes or synaptosomes allow the quantification of the microglia phagocytic abilities, while co-cultures of microglia and neurons, deriving from either WT or genetically modified mice models, provide a relatively manageable setting to investigate the involvement of specific molecular pathways. Further detailed analysis in mice brain is then mandatory to validate the in vitro assays as representative for the in vivo situation. The present review aims to dissect the main technical approaches to investigate microglia-mediated phagocytosis of neuronal and synaptic substrates in critical developmental time windows.

Towards the Development of Long Circulating Phosphatidylserine (PS)- and Phosphatidylglycerol (PG)-Enriched Anti-Inflammatory Liposomes: Is PEGylation Effective?

The anionic phospholipids (PLs) phosphatidylserine (PS) and phosphatidylglycerol (PG) are endogenous phospholipids with anti-inflammatory and immunomodulatory activity. A potential clinical use requires well-defined systems and for several applications, a long circulation time is desirable. Therefore, we aimed the development of long circulating liposomes with intrinsic anti-inflammatory activity. Hence, PS- and PG-enriched liposomes were produced, whilst phosphatidylcholine (PC) liposomes served as control. Liposomes were either formulated as conventional or PEGylated formulations. They had diameters below 150 nm, narrow size distributions and composition-dependent surface charges. Pharmacokinetics were assessed non-invasively via in vivo fluorescence imaging (FI) and ex vivo in excised organs over 2 days. PC liposomes, conventionally formulated, were rapidly cleared from the circulation, while PEGylation resulted in prolongation of liposome circulation robustly distributing among most organs. In contrast, PS and PG liposomes, both as conventional or PEGylated formulations, were rapidly cleared. Non-PEGylated PS and PG liposomes did accumulate almost exclusively in the liver. In contrast, PEGylated PS and PG liposomes were observed mainly in liver and spleen. In summary, PEGylation of PS and PG liposomes was not effective to prolong the circulation time but caused a higher uptake in the spleen.

Extracellular cardiolipin modulates microglial phagocytosis and cytokine secretion in a toll-like receptor (TLR) 4-dependent manner

Microglia-driven neuroinflammation contributes to neurodegenerative diseases. Mitochondrial phospholipid cardiolipin acts as a signaling molecule when released from damaged cells. We demonstrate that extracellular cardiolipin induces the secretion of monocyte chemoattractant protein-1 and interferon gamma-induced protein 10 by resting microglia while inhibiting secretion of cytokines by microglia stimulated with lipopolysaccharide, amyloid Aβ42 peptides, or α-synuclein. Extracellular cardiolipin also induces nitric oxide secretion by microglia-like cells and upregulates microglial phagocytosis. By using blocking antibodies, we determine that toll-like receptor 4 mediates the latter effect. Under physiological and pathological conditions characterized by cell death, extracellularly released cardiolipin may regulate immune responses of microglia.

Targeting Tumor-Associated Macrophages by MMP2-Sensitive Apoptotic Body-Mimicking Nanoparticles

Tumor-associated macrophages (TAMs), a major player in the tumor microenvironment, were recently recognized as a potential therapeutic target. To date, very few anticancer drugs or drug-delivery systems were designed to target the TAMs. Inspired by the "eat me" signal, phosphatidylserine (PS), mediated phagocytic clearance of apoptotic bodies, in this study, the matrix metalloproteinase 2 (MMP2)-sensitive PS-modified nanoparticles were developed. In the design, the PS is externalized to the nanoparticles' surface only when the nanoparticles reach the MMP2-overexpressing tumor site, allowing for the TAM-specific phagocytosis. The nanoparticles' excellent macrophage/TAM selectivity was observed in various biological models, including various cell lines, coculture cells, coculture cell spheroids, zebrafish, and tumor-bearing mice. The nanoparticles' TAM specificity remarkably enhanced the TAM depletion capability of the loaded model drug, dasatinib, resulting in the improved anticancer activity. The MMP2-sensitive apoptotic body-mimicking nanoparticles might be a promising delivery tool for TAM-centered cancer diagnoses and treatments.

Combination therapy of phosphatidylserine liposome with cyclosporine A improves nephrotoxicity and attenuates delayed-type hypersensitivity response

This study aimed to evaluate the antioxidant capacity of phosphatidylserine liposome (PS) against oxidative stress due to cyclosporine A (CsA) and concurrent administration of PS and CsA on the attenuation of immune response. The effect of oral PS was evaluated on biochemical and oxidative renal markers and histopathology of nephrotic rats receiving CsA. The effect of co-administration of PS with CsA was also assessed on DTH (delayed-type hypersensitivity) reaction of immunized rats. The cytokines production level of IL-2 (Interleukin-2) and IFN-γ (Interferon gamma) was measured in immunized rat's splenocytes. PS treatment significantly (P < 0.05) reduced Cr and BUN of serum and MDA (malondialdehyde) in kidney tissue, and increased SOD (superoxide dismutase) and CAT (Catalase) of kidney tissue in CsA-nephrotic rats. Histopathology data indicated significantly (P < 0.05) nephrotoxicity improvement after 25-day treatment with PS. Furthermore, CsA plus PS administration significantly reduced DTH response and cytokines production of IL-2 and IFN-γ in immunized rats. In conclusion, coadministration of CsA plus PS may overcome oxidative stress and improve the performance of organ transplantation or autoimmune therapy.

Phosphatidylserine (PS) and phosphatidylglycerol (PG) enriched mixed micelles (MM): A new nano-drug delivery system with anti-inflammatory potential?

Phosphatidylserine (PS) and phosphatidylglycerol (PG) are naturally occurring phospholipids (PL) with intrinsic anti-inflammatory properties. The therapeutic potential of PS and PG has not been extensively explored and the main focus had been directed towards PS- and PG-liposomes. In order to increase the formulation options, we explored whether mixed micelles (MM) could be an alternative to liposomes. Potential advantages of MM are their thermodynamic stability, small size and ease of manufacture. DOPS- and DOPG-enriched MM were obtained via a co-precipitation technique and physicochemical characterization was performed. The MM, approximately 10 nm in diameter, showed no toxicity on fibroblast cell lines in vitro and virtually no hemolytic activity. The MM suppressed the TNFα-production of mIFNγ/LPS-stimulated mouse peritoneal macrophages (MPM) in vitro similar to DOPS- and DOPG-liposomes. Therefore, DOPS- and DOPG-loaded MM are promising new options for the treatment of inflammatory diseases.

Metformin loaded phosphatidylserine nanoliposomes improve memory deficit and reduce neuroinflammation in streptozotocin-induced Alzheimer's disease model

Alzheimer's disease (AD) is closely associated with neuroinflammation development in the brain. Co-delivery of metformin (MET) with phosphatidylserine liposomes neuroprotectant may be beneficial in ameliorating AD-related symptoms like memory impairment and inflammation. Therefore, we aimed to prepare metformin containing phosphatidylserine nanoliposomes formulation (MET-PSL) and to evaluate its effect on rats subjected to AD. Alzheimer's disease model was induced by bilateral intracerebroventricular injection of streptozotocin (3 mg/kg) into rat brains using the stereotactic technique. MET-PSL, MET, and PSL alone were administered intraperitoneally to AD-induced animals and factors including learning and memory storage in addition to cytokine and tissue inflammatory changes were evaluated after a 22-day experiment period. The learning and memory parameters significantly (P < 0.05) improved in AD-rats treated with MET-PSL. Moreover, MET-PSL administration significantly (P < 0.05) decreased cytokine levels of IL1-β, TNF-α, and TGF-β in hippocampal tissues of rats with AD. Histological results indicated a considerable reduction in inflammatory and necrotic neural cells along with significantly (P < 0.05) increased neurogenesis in MET-PSL treated rats. Furthermore, our results showed that MET-PSL formulation could potentially act better than the free form of MET and PSL alone in the recovery process of rats with AD. In general, our data suggest that combination therapy of metformin loaded phosphatidylserine liposomes may enhance the therapeutic performance in AD patients of a clinical study.

Marine omega-3 (n-3) phospholipids: A comprehensive review of their properties, sources, bioavailability, and relation to brain health

For several decades, there has been considerable interest in marine-derived long chain n-3 fatty acids (n-3 LCPUFAs) due to their outstanding health benefits. n-3 LCPUFAs can be found in nature either in triglycerides (TAGs) or in phospholipid (PL) form. From brain health point of view, PL n-3 is more bioavailable and potent compared to n-3 in TAG form, as only PL n-3 is able to cross the blood-brain barrier and can be involved in brain biochemical reactions. However, PL n-3 has been ignored in the fish oil industry and frequently removed as an impurity during degumming processes. As a result, PL products derived from marine sources are very limited compared to TAG products. Commercially, PLs are being used in pharmaceutical industries as drug carriers, in food manufacturing as emulsifiers and in cosmetic industries as skin care agents, but most of the PLs used in these applications are produced from vegetable sources that contain less (without EPA, DPA, and DHA) or sometimes no n-3 LCPUFAs. This review provides a comprehensive account of the properties, structures, and major sources of marine PLs, and provides focussed discussion of their relationship to brain health. Epidemiological, laboratory, and clinical studies on n-3 LCPUFAs enriched PLs using different model systems in relation to brain and mental health that have been published over the past few years are discussed in detail.

In vitro antioxidant activity and in vivo wound-healing effect of lecithin liposomes: a comparative study

Aim: This study was conducted to determine the potentials of egg lecithin (egg-l) and soy lecithin (soy-l) liposomes in antioxidative and wound healing properties. Materials & methods: The suspensions of egg-l and soy-l were prepared using the fusion technique. The free radical scavenging activity of both lecithin liposomes was evaluated by DPPH and ABTS methods. Tissue staining was used to assess wound-healing parameter. Results: Liposomal lecithins showed an increasing trend of 1–10 mg/ml in radical-scavenging activities (p < 0.0001). Wound-healing assessments showed a significant effect (p < 0.0001) in treatment with topical lecithin liposomes. The results of wound healing also showed better outcomes of egg-l in comparison with phenytoin 1% cream. Conclusion: Antioxidant lecithin liposomes may enhance the treatment of wound injuries.

Natural barrigenol-like triterpenoids: A comprehensive review of their contributions to medicinal chemistry

Barrigenol-like triterpenoids (BATs), which contain an unusual oleanane substituted by many hydroxyl groups as the skeleton, are subdivided into five subtypes: barrigenol A₁, barrigenol A₂, barrigenol R₁, barringtogenol C, and 16-deoxybarringtogenol C. The variations in acyl derivatives, hydroxyl groups, and carbohydrate chains in their structures have enhanced the diversity of BATs. Moreover, the stable polyhydroxy-replaced pentacyclic skeleton provides an ideal platform for structural modifications. To date, more than 500 BAT derivatives have been isolated from plants. Synchronously, BATs possess anti-tumour, anti-Alzheimer's disease, anti-inflammatory, anti-microbial, anti-obesity and anti-allergic activities by regulating numerous cellular molecules. Some BAT derivatives, such as escin obtained from Aesculus hippocastanum L. and xanthoceraside isolated from Xanthoceras sorbifolia Bunge, have been used to treat encephaloedema or inflammatory diseases. This review aims to provide comprehensive information about the chemistry, sources, bioavailability, and anti-tumour effects of BATs, with a particular emphasis on the molecular mechanisms of action. The pharmacokinetics and clinical progress are also concerned. More than 300 structures identified over past 25 years are summarized here (249 compounds) and in the supplementary information (114 compounds). Accordingly, the pharmaceutical activity of barrigenol triterpenoids suggests that some compounds should be developed as promising anti-tumour or anti- Alzheimer's disease agents in future.

Extracellular cardiolipin regulates select immune functions of microglia and microglia-like cells

Cardiolipin is a mitochondrial membrane phospholipid with several well-defined metabolic roles. Cardiolipin can be released extracellularly by damaged cells and has been shown to affect peripheral immune functions. We hypothesized that extracellular cardiolipin can also regulate functions of microglia, the resident immune cells of the central nervous system (CNS). We demonstrate that extracellular cardiolipin increases microglial phagocytosis and neurotrophic factor expression, as well as decreases the release of inflammatory mediators and cytotoxins by activated microglia-like cells. These results identify extracellular cardiolipin as a potential CNS intercellular signaling molecule that can regulate key microglial immune functions associated with neurodegenerative diseases.

Apoptotic Cell-Mimetic Polymers for Anti-Inflammatory Therapy

The field of biomaterials has seen a strong rejuvenation due to the new potential to modulate immune system in our body. This special class of materials is called "immunomodulatory biomaterials". Generally, three fundamental strategies are followed in the design of immunomodulatory biomaterials: (1) immuno-inert biomaterials, (2) immuno-activating biomaterials, and (3) immuno-tolerant biomaterials. While many applications of immuno-inert biomaterials such as biocompatible medical implants have been already proposed in the past decades, the ability to engineer biological activity into synthetic materials greatly increases the number of their potential uses and improves their performance in more traditional applications. The major focus of researchers is now set on developing immuno-tolerant biomaterials for anti-inflammatory therapies. In this review, we therefore introduce recent developments of immuno-tolerant biomaterials. Especially we introduce an apoptotic cell membrane-inspired polymer and its post-inflammatory effects on immune cells in this article.

Manufacture and characterization of anti-inflammatory liposomes from jumbo flying squid (Dosidicus gigas) skin phospholipid extraction

The anti-inflammation properties of marine phospholipids enriched with n-3 fatty acids contribute to anti-inflammatory and inflammation-resolving mediators. Functional squid-skin (SQ) liposomes were manufactured from squid-skin phospholipids, and their anti-inflammatory effects were investigated. SQ liposomes included phosphatidylinositol (PI), phosphatidylserine (PS), phosphatidylethanolamine (PE), phosphatidylcholine (PC), and lysophosphatidylcholine (Lyso-PC), and had an approximate diameter of 100 mm. When RAW264.7 cells were treated with the SQ liposome, no (p > 0.05) cytotoxicity was observed below a concentration of 7.5 mg mL-1. An SQ-liposome pretreatment of lipopolysaccharide (LPS)-induced RAW 264.7 cells showed decreased (p < 0.05) prostaglandin E2 (PGE2), nitric oxide (NO), interleukin-1beta (IL-1β), IL-6, and tumor necrosis factor-alpha (TNF-α). The engulfment of SQ liposomes by the RAW264.7 cells resulted in lower (p < 0.05) LPS-induced intracellular levels of reactive oxygen species. Furthermore, an SQ-liposome administration ameliorated (p < 0.05) carrageenan-induced paw edema in mice. SQ liposomes may act via apoptotic mimicry to elicit the resolution of inflammation and prevent chronic inflammation-related diseases.

Alterations to the Intestinal Microbiome and Metabolome of Pimephales promelas and Mus musculus Following Exposure to Dietary Methylmercury

Mercury is a global contaminant, which may be microbially transformed into methylmercury (MeHg), which bioaccumulates. This results in potentially toxic body burdens in high trophic level organisms in aquatic ecosystems and maternal transfer to offspring. We previously demonstrated effects on developing fish including hyperactivity, altered time-to-hatch, reduced survival, and dysregulation of the dopaminergic system. A link between gut microbiota and central nervous system function in teleosts has been established with implications for behavior. We sequenced gut microbiomes of fathead minnows exposed to dietary MeHg to determine microbiome effects. Dietary exposures were repeated with adult CD-1 mice. Metabolomics was used to screen for metabolome changes in mouse brain and larval fish, and results indicate effects on lipid metabolism and neurotransmission, supported by microbiome data. Findings suggest environmentally relevant exposure scenarios may cause xenobiotic-mediated dysbiosis of the gut microbiome, contributing to neurotoxicity. Furthermore, small-bodied teleosts may be a useful model species for studying certain types of neurodegenerative diseases, in lieu of higher vertebrates.

Glycerophospholipid Supplementation as a Potential Intervention for Supporting Cerebral Structure in Older Adults

Modifying nutritional intake through supplementation may be efficacious for altering the trajectory of cerebral structural decline evident with increasing age. To date, there have been a number of clinical trials in older adults whereby chronic supplementation with B vitamins, omega-3 fatty acids, or resveratrol, has been observed to either slow the rate of decline or repair cerebral tissue. There is also some evidence from animal studies indicating that supplementation with glycerophospholipids (GPL) may benefit cerebral structure, though these effects have not yet been investigated in adult humans. Despite this paucity of research, there are a number of factors predicting poorer cerebral structure in older humans, which GPL supplementation appears to beneficially modify or protect against. These include elevated concentrations of homocysteine, unbalanced activity of reactive oxygen species both increasing the risk of oxidative stress, increased concentrations of pro-inflammatory messengers, as well as poorer cardio- and cerebrovascular function. As such, it is hypothesized that GPL supplementation will support cerebral structure in older adults. These cerebral effects may influence cognitive function. The current review aims to provide a theoretical basis for future clinical trials investigating the effects of GPL supplementation on cerebral structural integrity in older adults.

GABA-containing liposomes: neuroscience applications and translational perspectives for targeting neurological diseases

There are multiple challenges for neuropharmacology in the future. Undoubtedly, one of the greatest challenges is the development of strategies for pharmacological targeting of specific brain regions for treatment of diseases. GABA is the main inhibitory neurotransmitter in the central nervous system, and dysfunction of GABAergic mechanisms is associated with different neurological conditions. Liposomes are lipid vesicles that are able to encapsulate chemical compounds and are used for chronic drug delivery. This short review reports our experience with the development of liposomes for encapsulation and chronic delivery of GABA to sites within the brain. Directions for future research regarding the efficacy and practical use of GABA-containing liposomes for extended periods of time as well as understanding and targeting neurological conditions are discussed.

Apoptotic Cell Membrane-Inspired Polymer for Immunosuppression

Apoptotic cell death serves important roles in homeostasis by eliminating dangerous, damaged, or unnecessary cells without causing an inflammatory response by externalizing phosphatidylserine to the outer leaflet in the phospholipid bilayer. In this study, we newly designed apoptotic cell membrane-inspired monomer and polymer which have the phosphoryl serine group as the anti-inflammatory functional moiety and demonstrate here for the first time that administration of an apoptotic cell membrane-inspired phosphorylserine polymer can protect murine macrophages (RAW 264.7) from lipopolysaccharide-induced inflammation. Interestingly, statistical copolymers with phosphorylcholine monomer that mimicked more precisely the apoptotic cell membrane result in more effective suppression of macrophage activation. This study provides new insights into the rational design of effective polymeric materials for anti-inflammatory therapies.

Nanoliposome containing cyclosporine A reduced neuroinflammation responses and improved neurological activities in cerebral ischemia/reperfusion in rat

Cyclosporine A (CsA) is known as a neuroprotective agent against cerebral ischemia/reperfusion (I/R) in animal models. However, the significant therapeutic effects of CsA have been observed in high systemic doses or manipulating the blood-brain barrier, resulting in systemic side effects and toxicity. As the liposome nanocarriers have been developed for efficient delivery of peptide and proteins, liposomal CsA (Lipo-CsA) could improve cerebral (I/R) injuries. In this study, the liposomal CsA formulation (CsA at dose of 2.5 mg/kg) was prepared to assess the brain injury outcomes in 90 min middle cerebral artery occlusion (MCAO) stroke model followed by 48 h reperfusion in treating rats. Five minutes after induction of cerebral ischemia in rats, intravenous (iv) administration of Lipo-CsA significantly (P < 0.001) recovered the infarct size, the brain edema, and the neurological activities compared to corresponding control groups following 48 h I/R. In addition, after 48 h cerebral I/R, Lipo-CsA potentially (P < 0.001) inhibited the inflammation responses including MPO activity and tumor necrosis factor-alpha level in comparison to other groups. In conclusion, the results indicate that the low dose of CsA in liposomal formulation is more effective compared to higher dose of free form of CsA in treatment of ischemic brain in rats.

Electroconvulsive shock attenuated microgliosis and astrogliosis in the hippocampus and ameliorated schizophrenia-like behavior of Gunn rat

Background

Although electroconvulsive therapy (ECT) is regarded as one of the efficient treatments for intractable psychiatric disorders, the mechanism of therapeutic action remains unclear. Recently, many studies indicate that ECT affects the immune-related cells, such as microglia, astrocytes, and lymphocytes. Moreover, microglial activation and astrocytic activation have been implicated in the postmortem brains of schizophrenia patients. We previously demonstrated that Gunn rats showed schizophrenia-like behavior and microglial activation in their brains. The present study examined the effects of electroconvulsive shock (ECS), an animal counterpart of ECT, on schizophrenia-like behavior, microgliosis, and astrogliosis in the brain of Gunn rats.

Methods

The rats were divided into four groups, i.e., Wistar sham, Wistar ECS, Gunn sham, and Gunn ECS. ECS groups received ECS once daily for six consecutive days. Subsequently, prepulse inhibition (PPI) test was performed, and immunohistochemistry analysis was carried out to determine the activation degree of microglia and astrocytes in the hippocampus by using anti-CD11b and anti-glial fibrillary acidic protein (GFAP) antibody, respectively.

Results

We found PPI deficit in Gunn rats compared to Wistar rats, and it was significantly improved by ECS. Immunohistochemistry analysis revealed that immunoreactivity of CD11b and GFAP was significantly increased in Gunn rats compared to Wistar rats. ECS significantly attenuated the immunoreactivity of both CD11b and GFAP in Gunn rats.

Conclusions

ECS ameliorated schizophrenia-like behavior of Gunn rats and attenuated microgliosis and astrogliosis in the hippocampus of Gunn rats. Accordingly, therapeutic effects of ECT may be exerted, at least in part, by inhibition of glial activation. These results may provide crucial information to elucidate the role of activated glia in the pathogenesis of schizophrenia and to determine whether future therapeutic interventions should attempt to up-regulate or down-regulate glial functions.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-016-0688-2) contains supplementary material, which is available to authorized users.

"Eat me" imaging and therapy

Clearance of apoptotic debris is a vital role of the innate immune system. Drawing upon principles of apoptotic clearance, convenient delivery vehicles including intrinsic anti-inflammatory characteristics and specificity to immune cells can be engineered to aid in drug delivery. In this article, we examine the use of phosphatidylserine (PtdSer), the well-known "eat-me" signal, in nanoparticle-based therapeutics making them highly desirable "meals" for phagocytic immune cells. Use of PtdSer facilitates engulfment of nanoparticles allowing for imaging and therapy in various pathologies and may result in immunomodulation. Furthermore, we discuss the targeting of the macrophages and other cells at sites of inflammation in disease. A thorough understanding of the immunobiology of "eat-me" signals is requisite for the successful application of "eat-me"-bearing materials in biomedical applications.

Synergy between phenotypic modulation and ROS neutralization in reduction of inflammatory response of hypoxic microglia by using phosphatidylserine and antioxidant containing liposomes

Neuroinflammation caused by microglial activation is a key contributing factor in neurological disorders such as those involving ischaemia. Excess production of reactive oxygen species (ROS) and nitric oxide (NO) stimulates the inflammatory response during ischaemia, significantly damaging cells. Inhibition of inflammatory activation of microglia is a promising potential treatment approach for neurological diseases. In this study, we introduce α-tocopherol and phosphatidylserine (PS) containing liposomes (PST-liposomes) to inhibit the microglial inflammatory response. PS is known to have anti-inflammatory effects on microglia by modulating the microglial phenotype, while α-tocopherol is an antioxidant, known to neutralize ROS. We found that both PS-containing liposomes (PS-liposomes) and PST-liposomes, as compared with phosphatidylcholine containing liposomes, significantly increased viability of hypoxia-treated microglia. The PST-liposomes functioned better than the PS-liposomes and we attribute this superior effect to a synergy between PS and α-tocopherol. This synergic action of PST-liposomes was illustrated in their ability, when incubated with microglia, to reduce NO and pro-inflammatory cytokine (TNF-α) production and increase anti-inflammatory cytokine (TGF-β1) production. Thus, the improved viability of hypoxia-treated microglia when treated with PST-liposomes involved anti-inflammatory effects, including ROS neutralization, as well as induction of a microglial phenotypic change. Our results suggest that PST-liposomes represent a potential therapeutic approach to reducing ischaemic injury in the brain.

Therapeutic applications of reconstituted HDL: When structure meets function

Reconstituted forms of HDL (rHDL) are under development for infusion as a therapeutic approach to attenuate atherosclerotic vascular disease and to reduce cardiovascular risk following acute coronary syndrome and ischemic stroke. Currently available rHDL formulations developed for clinical use contain apolipoprotein A-I (apoA-I) and one of the major lipid components of HDL, either phosphatidylcholine or sphingomyelin. Recent data have established that quantitatively minor molecular constituents of HDL particles can strongly influence their anti-atherogenic functionality. Novel rHDL formulations displaying enhanced biological activities, including cellular cholesterol efflux, may therefore offer promising prospects for the development of HDL-based, anti-atherosclerotic therapies. Indeed, recent structural and functional data identify phosphatidylserine as a bioactive component of HDL; the content of phosphatidylserine in HDL particles displays positive correlations with all metrics of their functionality. This review summarizes current knowledge of structure-function relationships in rHDL formulations, with a focus on phosphatidylserine and other negatively-charged phospholipids. Mechanisms potentially underlying the atheroprotective role of these lipids are discussed and their potential for the development of HDL-based therapies highlighted.

The microglia in healthy and diseased retina

The microglia are the immune cells of the central nervous system and, also the retina. They fulfil several tasks of surveillance in the healthy retina. In case of an injury or disease, microglia become activated and tries to repair the damage. However, in a lot of cases it does not work, and microglia deteriorate the situation by releasing toxic and pro-inflammatory compounds. Moreover, they further promote degenerative processes by attacking and phagocytosing damaged neurones and photoreceptors that otherwise would possibly have the chance to survive. Such deleterious action of the microglia has been observed in degeneration of retinal ganglion cells and photoreceptors, and it takes place in hereditary diseases, infections as well as in case of traumatic or light injuries. Therefore, a number of attempts has been undertaken so far to inhibit the microglia, with varying success. The task remains to study behaviour of the microglia and their interaction with other retinal cell populations in more detail with respect to released factors and expressed receptors including the time points of the corresponding events. The goal has to be to find a better balance between helpful and detrimental actions of the microglia.

Phosphatidylserine containing omega-3 Fatty acids may improve memory abilities in nondemented elderly individuals with memory complaints: results from an open-label extension study

BACKGROUND

The present study is an open-label extension (OLE) aimed at evaluating the effect of 100 mg/day of phosphatidylserine enriched with docosahexaenoic acid (PS-DHA) on cognitive performance in nondemented elderly individuals with memory complaints.

METHODS

From the participants who completed the core study, 122 continued with a 15-week OLE. Efficacy was assessed using a computerized tool and the Clinical Global Impression of Change (CGI-C) rating scale.

RESULTS

A significant improvement in sustained attention and memory recognition was observed in the PS-DHA naïve group, while the PS-DHA continuers maintained their cognitive status. Additionally, a significant improvement in CGI-C was observed in the naïve group.

CONCLUSIONS

The results demonstrate that consumption of 100 mg/day of PS-DHA might be associated with improving or maintaining cognitive status in elderly subjects with memory complaints.

Introducing biobased ionic liquids as the nonaqueous media for enzymatic synthesis of phosphatidylserine

Biobased ionic liquids with cholinium as the cation and amino acids as the anions, which could be prepared from renewable biomaterials by simple neutralization reactions, have recently been described as promising and green solvents. Herein, they were successfully used as the reaction media for enzyme-mediated transphosphatidylation of phosphatidylcholine with l-serine for phosphatidylserine synthesis for the first time. Our results indicated that the highest phosphatidylserine yield of 86.5% was achieved. Moreover, 75% original activity of the enzyme was maintained after being used for 10 batches. The present work could be considered an alternative enzymatic strategy for preparing phosphatidylserine. Additionally, the excellent results make the biobased ionic liquids more promising candidates for use as environmentally friendly solvents in biocatalysis fields.

Tetramethylpyrazine, a natural alkaloid, attenuates pro-inflammatory mediators induced by amyloid β and interferon-γ in rat brain microglia

Neuroinflammation has been consistently reported as a pathological hallmark of Alzheimer׳s disease and other neurodegenerative diseases. Microglial cells are activated by diverse pathological stimuli and play key roles in development of neuroinflammation. Amyloid β peptide (Aβ), the major constituent of amyloid plaques in Alzheimer׳s brain, is known to activate cultured microglial cells to produce increased amounts of proinflammatory and neurotoxic factors. Tetramethylpyrazine (TMP) is the main bioactive alkaloid isolated from Ligusticum chuanxiong. TMP has multiple pharmacological activities, including anti-oxidant, anti-inflammatory, and anti-cancer effects. Neuroprotective potential of TMP has been demonstrated in animal models of neuropathologies. However, the efficacy of this compound for controlling Aβ-related neuropathology has not been explored yet. We examined the efficacy of TMP in the repression of inflammatory response in cultured microglial cells stimulated with Aβ25-35 in the presence of interferon (IFN)-γ. TMP significantly inhibited the Aβ25-35 and IFN-γ-stimulated productions of nitric oxide, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, monocyte chemoattractant protein-1, and intracellular reactive oxygen species from primary microglial cells. TMP also effectively reduced Aβ25-35 and IFN-γ-elicited NF-κB activation. In organotypic hippocampal slice cultures (OHSCs), TMP significantly blocked Aβ25-35-induced reactive oxygen species generation and phosphorylation of Akt. Furthermore, TMP also inhibited Aβ1-42-induced TNF-α and IL-1β production in primary microglial cells and neuronal death in OHSCs. These results suggest that TMP provide a possible therapeutic approach for alleviating the inflammatory progression of Alzheimer׳s disease.

Activation of microglia and induction of pro-inflammatory cytokines in the hippocampus of type 2 diabetic rats

OBJECTIVES

The majority of immune cells in the brain are comprised of microglia, which undergo morphological changes when activated to remove damaged neurons and infectious agents from the brain tissue. In this study, we investigated the effects of type 2 diabetes on microglial activation and the subsequent secretion of pro-inflammatory cytokines, such as interferon-gamma (IFN-gamma) and interleukin-1beta (IL-1beta), in the hippocampus using Zucker diabetic fatty (ZDF) rats and Zucker lean control (ZLC) rats at various diabetic stages.

METHODS

Zucker lean control and Zucker diabetic fatty rats were sacrificed at 12 (early diabetic stage), 20, or 30 weeks of age (chronic diabetic stage), and the hippocampus was obtained via transcardiac perfusion or dissection for immunohistochemistry and western blot analysis, respectively.

RESULTS

Zucker diabetic fatty rats demonstrated significantly higher glucose levels at 12 and 30 weeks of age compared to ZLC rats. Microglia immunoreactive to ionized calcium-binding adapter molecule 1 (Iba-1) had hypertrophied cytoplasm with retracted processes at 30 weeks of age. In contrast, Iba-1-immunoreactive microglia displayed similar morphology in ZDF and ZLC rats at 12 and 20 weeks of age. Similarly, IFN-gamma and IL-1beta protein levels were significantly increased in ZDF rats compared to ZLC rats at 30 weeks of age, but not at 12 and 20 weeks of age. Interleukin-1beta immunoreactivity in the ZDF rats predominantly increased in the dentate gyrus and CA1 region of the hippocampus compared to that of ZLC rats at 30 weeks of age. In addition, IL-1beta immunoreactive structures in ZDF rats at 30 weeks of age were detected near the astrocytes and microglia.

CONCLUSION

These results suggest that chronic diabetes activates microglia and significantly increases pro-inflammatory cytokine levels in the hippocampus.