Apolipoprotein E-derived peptides ameliorate clinical disability and inflammatory infiltrates into the spinal cord in a murine model of multiple sclerosis

An apolipoprotein E receptor mimetic peptide decreases blood-brain barrier permeability following intracerebral hemorrhage by inhibiting the CypA/MMP-9 signaling pathway via LRP1 activation

Apolipoprotein (Apo) E mimetic peptides down-regulate the inflammatory response and alleviate damage to secondary neurons after intracerebral hemorrhage (ICH). We designed a novel apoE receptor mimetic composed of the low-density lipoprotein receptor-associated protein-1 (LRP1) receptor-binding domain of apoE with 6 lysines (6KApoEp). The 6KApoEp peptide is small enough to penetrate the blood-brain barrier (BBB) and modulate the inflammatory response during damage to the central nervous system. LRP1 inhibits the CypA/MMP-9 pathway and reduces BBB damage. Thus, we examined the effects of 6KApoEp-LRP1 interaction. LRP1 and 6KApoEp interacted and co-localized in the pericytes. We established a Sprague-Dawley (SD) male rat model of ICH to observe the role of 6KApoEp in secondary injury after ICH. The expression levels of cyclophilin A (CypA), nuclear factor kappa-B (NF-κB) p65, and matrix metalloproteinase 9 (MMP-9) were increased, the expression levels of ZO-1, claudin-5, and occludin were decreased, and brain water content and BBB permeability increased in the ICH model. The expression of CypA, NF-κB, and MMP-9 decreased significantly around the hematoma, while the expression of tight junction-related proteins increased significantly in response to 6KApoEp, especially at the 100 μg/kg dose. LRP expression increased around the ICH focus in response to 6KApoEp treatment, thus increasing the influence on the expression of CypA, NF-κB, and MMP-9. We conclude that 6KApoEp inhibits the CypA/NF-κB/MMP-9 pathway by activating LRP1, resulting in reduced BBB damage and less brain edema around the ICH. These results provide the theoretical basis for improving the prognosis and treatment of ICH. Our results suggest that 6KApoEp activates LRP1, resulting in the attenuation of tight junction protein degradation (ZO-1, occludin, and claudin-5) via the CypA/NF-κB/MMP-9 signaling pathway. The increased tight junction protein levels improve the BBB and attenuate edema development in brain tissue around the hematoma following ICH.

The next decade of SET: from an oncoprotein to beyond

This year marks the fourth decade of research into the protein SET, which was discovered in 1992. SET was initially identified as an oncoprotein but later shown to be a multifaceted protein involved in regulating numerous biological processes under both physiological and pathophysiological conditions. SET dysfunction is closely associated with diseases, such as cancer and Alzheimer's disease. With the increasing understanding of how SET works and how it is regulated in cells, targeting aberrant SET has emerged as a potential strategy for disease intervention. In this review, we present a comprehensive overview of the advancements in SET studies, encompassing its biological functions, regulatory networks, clinical implications, and pharmacological inhibitors. Furthermore, we provide insights into the future prospects of SET research, with a particular emphasis on its promising potential in the realm of immune modulation.

Single-Cell Profiling Indicates a Proinflammatory Role of Meningeal Ectopic Lymphoid Tissue in Experimental Autoimmune Encephalomyelitis

BACKGROUND AND OBJECTIVES

The factors that drive progression in multiple sclerosis (MS) remain obscure. Identification of key properties of meningeal inflammation will contribute to a better understanding of the mechanisms of progression and how to prevent it.

METHODS

Applying single-cell RNA sequencing, we compared gene expression profiles in immune cells from meningeal ectopic lymphoid tissue (mELT) with those from secondary lymphoid organs (SLOs) in spontaneous chronic experimental autoimmune encephalomyelitis (EAE), an animal model of MS.

RESULTS

Generally, mELT contained the same immune cell types as SLOs, suggesting a close relationship. Preponderance of B cells over T cells, an increase in regulatory T cells and granulocytes, and a decrease in naïve CD4+ T cells characterize mELT compared with SLOs. Differential gene expression analysis revealed that immune cells in mELT show a more activated and proinflammatory phenotype compared with their counterparts in SLOs. However, the increase in regulatory T cells and upregulation of immunosuppressive genes in most immune cell types indicate that there are mechanisms in place to counter-regulate the inflammatory events, keeping the immune response emanating from mELT in check.

DISCUSSION

Common features in immune cell composition and gene expression indicate that mELT resembles SLOs and may be regarded as a tertiary lymphoid tissue. Distinct differences in expression profiles suggest that mELT rather than SLOs is a key driver of CNS inflammation in spontaneous EAE. Our data provide a starting point for further exploration of molecules or pathways that could be targeted to disrupt mELT formation.

Controlled Release of a Therapeutic Peptide in Sprayable Surgical Sealant for Prevention of Postoperative Abdominal Adhesions

Formation of asymmetric, rigid scar tissue known as surgical adhesions is caused by traumatic disruption of mesothelial-lined surfaces in surgery. A widely adopted prophylactic barrier material (Seprafilm) for the treatment of intra-abdominal adhesions is applied operatively as a pre-dried hydrogel sheet but has reduced translational efficacy due its brittle mechanical properties. Topically administered peritoneal dialysate (Icodextrin) and anti-inflammatory drugs have failed to prevent adhesions due to an uncontrolled release profile. Hence, inclusion of a targeted therapeutic into a solid barrier host matrix with improved mechanical properties could provide dual utility in adhesion prevention and as a surgical sealant. Spray deposition of poly(lactide-co-caprolactone) (PLCL) polymer fibers through solution blow spinning has yielded a tissue-adherent barrier material with previously reported adhesion prevention efficacy due to a surface erosion mechanism that inhibits deposition of inflamed tissue. However, such an approach uniquely presents an avenue for controlled therapeutic release through mechanisms of diffusion and degradation. Such a rate is kinetically tuned via facile blending of "high" molecular weight (HMW) and "low" molecular weight (LMW) PLCL with slow and fast biodegradation rates, respectively. Here, we explore viscoelastic blends of HMW PLCL (70% w/v) and LMW PLCL (30% w/v) as a host matrix for anti-inflammatory drug delivery. In this work, COG133, an apolipoprotein E (ApoE) mimetic peptide with potent anti-inflammatory properties was selected and tested. In vitro studies with PLCL blends presented low (∼30%) and high (∼80%) percent release profiles over a 14-day period based on the nominal molecular weight of the HMW PLCL component. Two independent mouse models of cecal ligation and cecal anastomosis significantly reduced adhesion severity versus Seprafilm, COG133 liquid suspension, and no treatment control. The synergy of physical and chemical methods in a barrier material with proven preclinical studies highlights the value of COG133-loaded PLCL fiber mats in effectively dampening the formation of severe abdominal adhesions.

Peptides as Pharmacological Carriers to the Brain: Promises, Shortcomings and Challenges

Central nervous system (CNS) diseases are among the most difficult to treat, mainly because the vast majority of the drugs fail to cross the blood-brain barrier (BBB) or to reach the brain at concentrations adequate to exert a pharmacological activity. The obstacle posed by the BBB has led to the in-depth study of strategies allowing the brain delivery of CNS-active drugs. Among the most promising strategies is the use of peptides addressed to the BBB. Peptides are versatile molecules that can be used to decorate nanoparticles or can be conjugated to drugs, with either a stable link or as pro-drugs. They have been used to deliver to the brain both small molecules and proteins, with applications in diverse therapeutic areas such as brain cancers, neurodegenerative diseases and imaging. Peptides can be generally classified as receptor-targeted, recognizing membrane proteins expressed by the BBB microvessels (e.g., Angiopep2, CDX, and iRGD), "cell-penetrating peptides" (CPPs; e.g. TAT_47-57, SynB1/3, and Penetratin), undergoing transcytosis through unspecific mechanisms, or those exploiting a mixed approach. The advantages of peptides have been extensively pointed out, but so far few studies have focused on the potential negative aspects. Indeed, despite having a generally good safety profile, some peptide conjugates may display toxicological characteristics distinct from those of the peptide itself, causing for instance antigenicity, cardiovascular alterations or hemolysis. Other shortcomings are the often brief lifetime in vivo, caused by the presence of peptidases, the vulnerability to endosomal/lysosomal degradation, and the frequently still insufficient attainable increase of brain drug levels, which remain below the therapeutically useful concentrations. The aim of this review is to analyze not only the successful and promising aspects of the use of peptides in brain targeting but also the problems posed by this strategy for drug delivery.

COG133 Attenuates the Early Brain Injury Induced by Blood-Brain Barrier Disruption in Experimental Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a kind of severe hemorrhagic stroke, and early brain injury acted as one of the main causes of death and delayed neurological deficit in patients with subarachnoid hemorrhage. In this process, the function and structural integrity of the blood-brain barrier play an important role. In this study, we have observed whether the apolipoprotein E (apoE) mimetic peptide, COG133, can alleviate early brain injury after subarachnoid hemorrhage. For this purpose, an experimental subarachnoid hemorrhage model was constructed in mice and treated by intravenous injection of COG133 at a dosage of 1 mg/kg. Then, the function and integrity of the blood-brain barrier were detected, and the pyroptosis level of the neuron was determined. The results showed that COG133 could protect blood-brain barrier function and structure integrity, reduce early brain injury, and ameliorate neurological function after subarachnoid hemorrhage. In terms of molecular mechanism, COG133 inhibits blood-brain barrier destruction through the proinflammatory CypA-NF-κB-MMP9 pathway and reduces neuronal pyroptosis by inhibiting NLRP3 inflammasome activation. In conclusion, this study demonstrated that apoE-mimetic peptide, COG133, can play a neuroprotective role by protecting blood-brain barrier function and inhibiting brain cell pyroptosis to reduce early brain injury after subarachnoid hemorrhage.

Effect of electroacupuncture on inhibition of inflammatory response and oxidative stress through activating ApoE and Nrf2 in a mouse model of spinal cord injury

INTRODUCTION

Electroacupuncture protects neurons and myelinated axons after spinal cord injury by mitigating the inflammatory response and oxidative stress, but how it exerts these effects is unclear.

METHODS AND RESULTS

Spinal cord injury was induced in C57BL/6 wild-type and apolipoprotein E (ApoE) knockout (ApoE^-/- ) mice, followed by electroacupuncture or ApoE mimetic peptide COG112 treatment. Mice with spinal cord injury suffered loss of myelinated axons and hindlimb motor function through the detections of Basso mouse scale, histology, and transmission electron microscopy; electroacupuncture partially reversed these effects in wild-type mice but not in ApoE^-/- mice. Combining exogenous ApoE administration with electroacupuncture significantly mitigated the effects of spinal cord injury in both mouse strains, and these effects were associated with up-regulation of anti-inflammatory cytokines and down-regulation of pro-inflammatory cytokines which were detected by quantitative reverse transcription-polymerase chain reaction. Combination treatment also reduced oxidative stress by up-regulating ApoE and Nrf2/HO-1 signaling pathway through the detections of immunofluorescence and western blot analysis.

CONCLUSIONS

These results suggest that electroacupuncture protects neurons and myelinated axons following spinal cord injury through an ApoE-dependent mechanism.

The Role of HDL and HDL Mimetic Peptides as Potential Therapeutics for Alzheimer's Disease

The role of high-density lipoproteins (HDL) in the cardiovascular system has been extensively studied and the cardioprotective effects of HDL are well established. As HDL particles are formed both in the systemic circulation and in the central nervous system, the role of HDL and its associated apolipoproteins in the brain has attracted much research interest in recent years. Alzheimer’s disease (AD) is the most prevalent neurodegenerative disorder and the leading cause of dementia worldwide, for which there currently exists no approved disease modifying treatment. Multiple lines of evidence, including a number of large-scale human clinical studies, have shown a robust connection between HDL levels and AD. Low levels of HDL are associated with increased risk and severity of AD, whereas high levels of HDL are correlated with superior cognitive function. Although the mechanisms underlying the protective effects of HDL in the brain are not fully understood, many of the functions of HDL, including reverse lipid/cholesterol transport, anti-inflammation/immune modulation, anti-oxidation, microvessel endothelial protection, and proteopathy modification, are thought to be critical for its beneficial effects. This review describes the current evidence for the role of HDL in AD and the potential of using small peptides mimicking HDL or its associated apolipoproteins (HDL-mimetic peptides) as therapeutics to treat AD.

Cationic Arginine-Rich Peptides (CARPs): A Novel Class of Neuroprotective Agents With a Multimodal Mechanism of Action

There are virtually no clinically available neuroprotective drugs for the treatment of acute and chronic neurological disorders, hence there is an urgent need for the development of new neuroprotective molecules. Cationic arginine-rich peptides (CARPs) are an expanding and relatively novel class of compounds, which possess intrinsic neuroprotective properties. Intriguingly, CARPs possess a combination of biological properties unprecedented for a neuroprotective agent including the ability to traverse cell membranes and enter the CNS, antagonize calcium influx, target mitochondria, stabilize proteins, inhibit proteolytic enzymes, induce pro-survival signaling, scavenge toxic molecules, and reduce oxidative stress as well as, having a range of anti-inflammatory, analgesic, anti-microbial, and anti-cancer actions. CARPs have also been used as carrier molecules for the delivery of other putative neuroprotective agents across the blood-brain barrier and blood-spinal cord barrier. However, there is increasing evidence that the neuroprotective efficacy of many, if not all these other agents delivered using a cationic arginine-rich cell-penetrating peptide (CCPPs) carrier (e.g., TAT) may actually be mediated largely by the properties of the carrier molecule, with overall efficacy further enhanced according to the amino acid composition of the cargo peptide, in particular its arginine content. Therefore, in reviewing the neuroprotective mechanisms of action of CARPs we also consider studies using CCPPs fused to a putative neuroprotective peptide. We review the history of CARPs in neuroprotection and discuss in detail the intrinsic biological properties that may contribute to their cytoprotective effects and their usefulness as a broad-acting class of neuroprotective drugs.

Novel Blood-Brain Barrier Shuttle Peptides Discovered through the Phage Display Method

Delivery of therapeutic agents into the brain is a major challenge in central nervous system drug development. The blood–brain barrier (BBB) prevents access of biotherapeutics to their targets in the central nervous system and, therefore, prohibits the effective treatment of many neurological disorders. To find blood–brain barrier shuttle peptides that could target therapeutics to the brain, we applied a phage display technology on a primary endothelial rat cellular model. Two identified peptides from a 12 mer phage library, GLHTSATNLYLH and VAARTGEIYVPW, were selected and their permeability was validated using the in vitro BBB model. The permeability of peptides through the BBB was measured by ultra-performance liquid chromatography-tandem mass spectrometry coupled to a triple-quadrupole mass spectrometer (UHPLC-MS/MS). We showed higher permeability for both peptides compared to N–C reversed-sequence peptides through in vitro BBB: for peptide GLHTSATNLYLH 3.3 × 10⁻⁷ cm/s and for peptide VAARTGEIYVPW 1.5 × 10⁻⁶ cm/s. The results indicate that the peptides identified by the in vitro phage display technology could serve as transporters for the administration of biopharmaceuticals into the brain. Our results also demonstrated the importance of proper BBB model for the discovery of shuttle peptides through phage display libraries.

The future of apolipoprotein E mimetic peptides in the prevention of cardiovascular disease

PURPOSE OF REVIEW

This review aims to discuss the recent developments in the area of apolipoprotein E (apoE) mimetics and their therapeutic potential for treating cardiovascular disease, the leading cause of mortality worldwide.

RECENT FINDINGS

Ongoing research efforts target the development of novel therapies that would not only reduce circulating levels of atherogenic lipoproteins, but could also increase high density lipoprotein cholesterol (HDL-C) levels and/or improve HDL function. Among them, synthetic peptides that mimic the structure of natural human apoE, a component of triglyceride-rich lipoproteins and HDL, have been designed and proven to be functionally similar to apoE. In specific, apoE mimetic peptides mediate hepatic clearance of circulating atherogenic lipoproteins, dramatically reduce plasma cholesterol, and lead to attenuation of atherosclerosis development in vivo. These peptides also exhibit pleiotropic antiatherogenic properties, such as macrophage cholesterol efflux capacity, as well as anti-inflammatory and antioxidative functions.

SUMMARY

ApoE mimetics are undergoing preclinical and clinical evaluation with promising results to date that render them attractive candidates in cardiovascular disease prevention and treatment.

Lifestyle-based modifiable risk factors in multiple sclerosis: review of experimental and clinical findings

Multiple sclerosis (MS) is a lifelong inflammatory and neurodegenerative disease influenced by multiple lifestyle-based factors. We provide a narrative review of the effects of modifiable risk factors that are identified as being associated with risk to develop MS and/or influencing the future clinical disease outcomes. The emerging data regarding the beneficial effects of diet modifications and exercise are further reviewed. In contrast, obesity and comorbid cardiovascular diseases are associated with increased MS susceptibility and worse disease progression. In addition, the potential influence of smoking, coffee and alcohol consumption on MS onset and disability development are discussed. Successful management of the modifiable risk factors may lead to better long-term outcomes and improve patients' quality of life. MS specialists should participate in educating and facilitating lifestyle-based modifications as part of their neurological consults.

Understanding the Role of ApoE Fragments in Alzheimer's Disease

Alzheimer's disease (AD) is one of the most devastating neurodegenerative diseases. It has been known for decades that the APOE ɛ4 allele is the most significant genetic risk factor for late-onset AD and yet its precise role in the disease remains unclear. The APOE gene encodes apolipoprotein E (apoE), a 35 kDa glycoprotein highly expressed in the brain. There are three different isoforms: apoE3 is the most common allele in the population, whilst apoE2 decreases, and apoE4 increases AD risk. ApoE has numerous functions that affect neuronal and non-neuronal cells, thus how it contributes to disease onset and progression is hotly debated. The apoE4 isoform has been linked to the accumulation of both of the major pathological hallmarks of AD, amyloid plaques containing amyloid β peptides, and neurofibrillary tangles containing hyperphosphorylated tau protein, as well as other hallmarks of the disease, including inflammation and oxidative stress. Numerous studies have shown that apoE undergoes fragmentation in the human brain, and that the fragmentation pattern varies between isoforms. It was previously shown that apoE4 has neurotoxic functions, however recent data has also identified a neuroprotective role for the apoE N-terminal 25 kDa fragment, which is more prevalent in apoE3 individuals. The ability of the apoE 25 kDa fragment to promote neurite outgrowth was recently demonstrated and this suggests there is a potential loss of neuroprotection in apoE4 individuals in addition to the previously described gain of toxic function for specific apoE4 fragments. Here we review the enzymes proposed to be responsible for apoE fragmentation, the specific functions of different apoE fragments and their possible links with AD.

Apolipoprotein E mimetic peptide CN-105 improves outcome in a murine model of SAH

Objective

Subarachnoid haemorrhage (SAH) accounts for 3% of all strokes, and is associated with significant morbidity and mortality. There is growing evidence implicating apolipoprotein E (apoE) in mediating adaptive anti-inflammatory and neuroprotective responses following ischaemic and traumatic brain injury. In the current study, we test the efficacy of a small apoE mimetic peptide, CN-105 in a murine model of SAH.

Methods

Mice subjected to SAH received repeated intravenous injections of CN-105 every 12 hours for 3 days, with the first dose given 2 hours after injury. Daily functional outcomes were assessed by rotarod and neurological severity score. Haemorrhage grade and cerebral vascular diameters were measured at 5 days post-SAH. Cerebral microgliosis, neuronal degeneration and survival were analysed at 5 and 35 days post-SAH, respectively.

Results

CN-105 reduces histological evidence of inflammation, reduces vasospasm and neuronal injury and is associated with improved long-term behavioural outcomes in a murine model of SAH.

Conclusions

Given its favourable pharmacokinetic profile, central nervous system penetration and demonstration of clinical safety, CN-105 represents an attractive therapeutic candidate for treatment of brain injury associated with SAH.

Metabolic Dysfunction and Peroxisome Proliferator-Activated Receptors (PPAR) in Multiple Sclerosis

Multiple sclerosis (MS) is an inflammatory and neurodegenerative disease of the central nervous system (CNS) probably caused, in most cases, by the interaction of genetic and environmental factors. This review first summarizes some clinical, epidemiological and pathological characteristics of MS. Then, the involvement of biochemical pathways is discussed in the development and repair of the CNS lesions and the immune dysfunction in the disease. Finally, the potential roles of peroxisome proliferator-activated receptors (PPAR) in MS are discussed. It is suggested that metabolic mechanisms modulated by PPAR provide a window to integrate the systemic and neurological events underlying the pathogenesis of the disease. In conclusion, the reviewed data highlight molecular avenues of understanding MS that may open new targets for improved therapies and preventive strategies for the disease.

A comprehensive and perspective view of oncoprotein SET in cancer

SET is a multifunctional oncoprotein which is ubiquitously expressed in all kinds of cells. The SET protein participates in many cellular processes including cell cycle, cell migration, apoptosis, transcription, and DNA repair. Accumulating evidence demonstrates that the expression and activity of SET correlate with cancer occurrence, metastasis, and prognosis. Therefore, the SET protein is regarded as a potential target for cancer therapy and several inhibitors are being developed for clinical use. Herein, we comprehensively review the physiological and pathological functions of SET as well as its structure-function relationship. Additionally, the regulatory mechanisms of SET at both transcriptional and posttranslational levels are also discussed.

The serine protease HtrA1 contributes to the formation of an extracellular 25-kDa apolipoprotein E fragment that stimulates neuritogenesis

Apolipoprotein-E (apoE) is a glycoprotein highly expressed in the brain, where it appears to play a role in lipid transport, β-amyloid clearance, and neuronal signaling. ApoE proteolytic fragments are also present in the brain, but the enzymes responsible for apoE fragmentation are unknown, and the biological activity of specific apoE fragments remains to be determined. Here we utilized SK-N-SH neuroblastoma cells differentiated into neurons with all-trans-retinoic acid (ATRA) to study extracellular apoE proteolysis. ApoE fragments were detectable in culture supernatants after 3 days, and their levels were increased for up to 9 days in the presence of ATRA. The concentration of apoE fragments was positively correlated with levels of the neuronal maturation markers (PSD95 and SMI32). The most abundant apoE fragments were 25- and 28-kDa N-terminal fragments that both contained sialylated glycosylation and bound to heparin. We detected apoE fragments only in the extracellular milieu and not in cell lysates, suggesting that an extracellular protease contributes to apoE fragmentation. Of note, siRNA-mediated knockdown of high-temperature requirement serine peptidase A1 (HtrA1) and a specific HtrA1 inhibitor reduced apoE 25-kDa fragment formation by 41 and 86%, respectively. Recombinant 25-kDa fragment apoE and full-length apoE both stimulated neuritogenesis in vitro, increasing neuroblastoma neurite growth by more than 2-fold over a 6-day period. This study provides a cellular model for assessing apoE proteolysis, indicates that HtrA1 regulates apoE 25-kDa fragment formation under physiological conditions, and reveals a new neurotrophic function for the apoE 25-kDa fragment.

Low-Density Lipoprotein Receptor Deficiency Attenuates Neuroinflammation through the Induction of Apolipoprotein E

Objective

We aimed to determine the role of the low-density lipoprotein receptor (LDLr) in neuroinflammation by inducing experimental autoimmune encephalomyelitis (EAE) in ldlr knock out mice.

Methods

MOG_35-55 induced EAE in male and female ldlr^-/- mice was assessed clinically and histopathologically. Expression of inflammatory mediators and apolipoprotein E (apoE) was investigated by qPCR. Changes in protein levels of apoE and tumor necrosis factor alpha (TNFα) were validated by western blot and ELISA, respectively.

Results

Ldlr^-/--attenuated EAE disease severity in female, but not in male, EAE mice marked by a reduced proinflammatory cytokine production in the central nervous system of female ldlr^-/- mice. Macrophages from female ldlr^-/- mice showed a similar decrease in proinflammatory mediators, an impaired capacity to phagocytose myelin and enhanced secretion of the anti-inflammatory apoE. Interestingly, apoE/ldlr double knock out abrogated the beneficial effect of ldlr depletion in EAE.

Conclusion

Collectively, we show that ldlr^-/- reduces EAE disease severity in female but not in male EAE mice, and that this can be explained by increased levels of apoE in female ldlr^-/- mice. Although the reason for the observed sexual dimorphism remains unclear, our findings show that LDLr and associated apoE levels are involved in neuroinflammatory processes.

Apolipoprotein E as a novel therapeutic neuroprotection target after traumatic spinal cord injury

Apolipoprotein E (apoE), a plasma lipoprotein well known for its important role in lipid and cholesterol metabolism, has also been implicated in many neurological diseases. In this study, we examined the effect of apoE on the pathophysiology of traumatic spinal cord injury (SCI). ApoE-deficient mutant (apoE^-/-) and wild-type mice received a T9 moderate contusion SCI and were evaluated using histological and behavioral analyses after injury. At 3days after injury, the permeability of spinal cord-blood-barrier, measured by extravasation of Evans blue dye, was significantly increased in apoE^-/- mice compared to wild type. The inflammation and spared white matter was also significantly increased and decreased, respectively, in apoE^-/- mice compared to the wild type ones. The apoptosis of both neurons and oligodendrocytes was also significantly increased in apoE^-/- mice. At 42days after injury, the inflammation was still robust in the injured spinal cord in apoE^-/- but not wild type mice. CD45+ leukocytes from peripheral blood persisted in the injured spinal cord of apoE^-/- mice. The spared white matter was significantly decreased in apoE^-/- mice compared to wild type ones. Locomotor function was significantly decreased in apoE^-/- mice compared to wild type ones from week 1 to week 8 after contusion. Treatment of exogenous apoE mimetic peptides partially restored the permeability of spinal cord-blood-barrier in apoE^-/- mice after SCI. Importantly, the exogenous apoE peptides decreased inflammation, increased spared white matter and promoted locomotor recovery in apoE^-/- mice after SCI. Our results indicate that endogenous apoE plays important roles in maintaining the spinal cord-blood-barrier and decreasing inflammation and spinal cord tissue loss after SCI, suggesting its important neuroprotective function after SCI. Our results further suggest that exogenous apoE mimetic peptides could be a novel and promising neuroprotective reagent for SCI.

OP449 inhibits breast cancer growth without adverse metabolic effects

Hyperinsulinemia is associated with a decrease in breast cancer recurrence-free survival and overall survival. Inhibition of insulin receptor signaling is associated with glycemic dysregulation. SET is a direct modulator of PP2A, which negatively regulates the PI3K/AKT/mTOR pathway. OP449, a SET inhibitor, decreases AKT/mTOR activation. The effects of OP449 treatment on breast cancer growth in the setting of pre-diabetes, and its metabolic implications are currently unknown. We found that the volumes and weights of human MDA-MB-231 breast cancer xenografts were greater in hyperinsulinemic mice compared with controls (P < 0.05), and IR phosphorylation was 4.5-fold higher in these mice (P < 0.05). Human and murine breast cancer tumors treated with OP449 were 47% and 39% smaller than controls (P < 0.05, for both, respectively). AKT and S6RP phosphorylation were 82% and 34% lower in OP449-treated tumors compared with controls (P < 0.05, P = 0.06, respectively). AKT and S6RP phosphorylation in response to insulin was 30% and 12% lower in cells, pre-treated with OP449, compared with control cells (P < 0.01, P < 0.05, respectively). However, even with decreased AKT/mTOR activation, body weights and composition, blood glucose and plasma insulin, glucose tolerance, serum triglyceride and cholesterol levels were similar between OP449-treated mice and controls. Xenografts and liver tissue from OP449-treated mice showed a 64% and 70% reduction in STAT5 activation, compared with controls (P < 0.01 and P = 0.06, respectively). Our data support an anti-neoplastic effect of OP449 on human breast cancer cells in vitro and in xenografts in the setting of hyperinsulinemia. OP449 led to the inhibition of AKT/mTOR signaling, albeit, not leading to metabolic derangements.

ApoE deficiency promotes colon inflammation and enhances inflammatory potential oxidized-LDL and TNF-α in colon epithelial cells

Although deficiency in Apolipoprotein E (ApoE) is linked to many diseases, its effect on colon homoeostasis remains unknown. ApoE appears to control inflammation by regulating nuclear factor-κB (NF-κB). The present study was designed to examine whether ApoE deficiency affects factors of colon integrity in vivo and given the likelihood that ApoE deficiency increases oxidized lipids and TNF-α, the present study also examined whether such deficiency enhances the inflammatory potential of oxidized-LDL (oxLDL) and TNF-α in colon epithelial cells (CECs), in vitro. Here we show that ApoE deficiency is associated with chronic inflammation systemically and in colonic tissues as assessed by TNF-α levels. Increased colon TNF-α mRNA coincided with a substantial increase in cyclooxygenase (COX)-2. ApoE deficiency enhanced the potential of oxLDL and TNF-α to induce COX-2 expression as well as several other inflammatory factors in primary CECs. Interestingly, oxLDL enhanced TGF-β expression only in ApoE^−/−, but not in wild-type, epithelial cells. ApoE deficiency appears to promote COX-2 expression enhancement through a mechanism that involves persistent NF-κB nuclear localization and PI3 and p38 MAP kinases but independently of Src. In mice, ApoE deficiency promoted a moderate increase in crypt length, which was associated with opposing effects of an increase in cell proliferation and apoptosis at the bottom and top of the crypt respectively. Our results support the notion that ApoE plays a central role in colon homoeostasis and that ApoE deficiency may constitute a risk factor for colon pathologies.

Inhibition of Interleukin-10 Signaling Induces Microbiota-dependent Chronic Colitis in Apolipoprotein E Deficient Mice

BACKGROUND

Apolipoprotein E (ApoE) mediates potent antiinflammatory and immunomodulatory properties in addition to its roles in regulating cholesterol transport and metabolism. However, its role in the intestine, specifically during inflammation, is largely unknown.

METHODS

Mice (C57BL/6 or ApoE-deficient [ApoE-KO] mice) were administered either single or 4 injections (weekly) of anti-interleukin (IL)-10 receptor monoclonal antibody (1.0 mg/mouse; intraperitoneally) and euthanized 1 week after the last injection. 16S rRNA sequencing was performed in fecal samples to analyze the gut bacterial load and its composition. Microbiota was ablated by administration of broad-spectrum antibiotics in drinking water. IL-10KO mice were cohoused with ApoE-KO mice or their wild-type littermates to monitor the colitogenic potential of gut microbiota harbored in ApoE-KO mice.

RESULTS

ApoE-KO mice developed severe colitis upon neutralization of IL-10 signaling as assessed by every parameter analyzed. 16S rRNA sequencing revealed that the ApoE-KO mice display elevated and altered gut microbiota that were accompanied with impaired production of intestinal antimicrobial peptides. Interestingly, microbiota ablation ameliorates colitis development in ApoE-KO mice. Exacerbated and accelerated colitis was observed in IL-10KO mice when cohoused with ApoE-KO mice.

CONCLUSIONS

Our study highlights a novel interplay between ApoE and IL-10 in maintaining gut homeostasis and that such crosstalk may play a critical role in the pathogenesis of inflammatory bowel disease. Gut sterilization and the cohousing experiment suggest that microbiota play a pivotal role in the development of inflammatory bowel disease in mice lacking ApoE.

Promising approaches to circumvent the blood-brain barrier: progress, pitfalls and clinical prospects in brain cancer

Brain drug delivery is a major challenge for therapy of central nervous system (CNS) diseases. Biochemical modifications of drugs or drug nanocarriers, methods of local delivery, and blood-brain barrier (BBB) disruption with focused ultrasound and microbubbles are promising approaches which enhance transport or bypass the BBB. These approaches are discussed in the context of brain cancer as an example in CNS drug development. Targeting to receptors enabling transport across the BBB offers noninvasive delivery of small molecule and biological cancer therapeutics. Local delivery methods enable high dose delivery while avoiding systemic exposure. BBB disruption with focused ultrasound and microbubbles offers local and noninvasive treatment. Clinical trials show the prospects of these technologies and point to challenges for the future.

Neuroprotective peptides fused to arginine-rich cell penetrating peptides: Neuroprotective mechanism likely mediated by peptide endocytic properties

Several recent studies have demonstrated that TAT and other arginine-rich cell penetrating peptides (CPPs) have intrinsic neuroprotective properties in their own right. Examples, we have demonstrated that in addition to TAT, poly-arginine peptides (R8 to R18; containing 8-18 arginine residues) as well as some other arginine-rich peptides are neuroprotective in vitro (in neurons exposed to glutamic acid excitotoxicity and oxygen glucose deprivation) and in the case of R9 in vivo (after permanent middle cerebral artery occlusion in the rat). Based on several lines of evidence, we propose that this neuroprotection is related to the peptide's endocytosis-inducing properties, with peptide charge and arginine residues being critical factors. Specifically, we propose that during peptide endocytosis neuronal cell surface structures such as ion channels and transporters are internalised, thereby reducing calcium influx associated with excitotoxicity and other receptor-mediated neurodamaging signalling pathways. We also hypothesise that a peptide cargo can act synergistically with TAT and other arginine-rich CPPs due to potentiation of the CPPs endocytic traits rather than by the cargo-peptide acting directly on its supposedly intended intracellular target. In this review, we systematically consider a number of studies that have used CPPs to deliver neuroprotective peptides to the central nervous system (CNS) following stroke and other neurological disorders. Consequently, we critically review evidence that supports our hypothesis that neuroprotection is mediated by carrier peptide endocytosis. In conclusion, we believe that there are strong grounds to regard arginine-rich peptides as a new class of neuroprotective molecules for the treatment of a range of neurological disorders.

"Disease modifying nutricals" for multiple sclerosis

The association between vitamin D and multiple sclerosis has (re)-opened new interest in nutrition and natural compounds in the prevention and treatment of this neuroinflammatory disease. The dietary amount and type of fat, probiotics and biologicals, salmon proteoglycans, phytoestrogens and protease inhibitor of soy, sodium chloride and trace elements, and fat soluble vitamins including D, A and E were all considered as disease-modifying nutraceuticals. Studies in experimental autoimmune encephalomyelitis mice suggest that poly-unsaturated fatty acids and their 'inflammation-resolving' metabolites and the gut microflora may reduce auto-aggressive immune cells and reduce progression or risk of relapse, and infection with whipworm eggs may positively change the gut-brain communication. Encouraged by the recent interest in multiple sclerosis-nutrition nature's pharmacy has been searched for novel compounds with anti-inflammatory, immune-modifying and antioxidative properties, the most interesting being the scorpion toxins that inhibit specific potassium channels of T cells and antioxidative compounds including the green tea flavonoid epigallocatechin-3-gallate, curcumin and the mustard oil glycoside from e.g. broccoli and sulforaphane. They mostly also inhibit pro-inflammatory signaling through NF-κB or toll-like receptors and stabilize the blood brain barrier. Disease modifying functions may also complement analgesic and anti-spastic effects of cannabis, its constituents, and of 'endocannabinoid enhancing' drugs or nutricals like inhibitors of fatty acid amide hydrolase. Nutricals will not solve multiple sclerosis therapeutic challenges but possibly support pharmacological interventions or unearth novel structures.

Anti-inflammatory and cholesterol-reducing properties of apolipoprotein mimetics: a review

Reduced levels of HDL cholesterol (HDL-C) are a strong independent predictor of coronary artery disease (CAD) risk. The major anti-atherogenic function of HDL is to mediate reverse cholesterol transport. This response is highly dependent on apoA-I and apoE, protein components of HDL. Randomized clinical trials have assessed effects of several classes of drugs on plasma cholesterol levels in CAD patients. Agents including cholestyramine, fibrates, niacin, and statins significantly lower LDL cholesterol (LDL-C) and induce modest increases in HDL-C, but tolerance issues and undesirable side effects are common. Additionally, residual risk may be present in patients with persistently low HDL-C and other complications despite a reduction in LDL-C. These observations have fueled interest in the development of new pharmacotherapies that positively impact circulating lipoproteins. The goal of this review is to discuss the therapeutic potential of synthetic apolipoprotein mimetic peptides. These include apoA-I mimetic peptides that have undergone initial clinical assessment. We also discuss newer apoE mimetics that mediate the clearance of atherogenic lipids from the circulation and possess anti-inflammatory properties. One of these (AEM-28) has recently been given orphan drug status and is undergoing clinical trials.

An apolipoprotein E mimetic peptide with activities against multidrug-resistant bacteria and immunomodulatory effects

Apolipoprotein E (apoE) mimetic peptides derived from the low-density lipoprotein receptor-binding region of apoE with both activities against multidrug-resistant bacteria and immunomodulatory effects have not previously been reported. We identified an apoE mimetic peptide analogue of the receptor-binding region of apoE (abbreviated as apoE23) with the sequence of LRKLRKRLVRLASHLRKLRKRLL, which exhibited high antibacterial effects. The minimal inhibitory concentration of apoE23 against multidrug-resistant Acinetobacter baumannii was 6 µg/ml. The antimicrobial activity of apoE23 depended on its amphipathic α-helical conformation. Moreover, apoE23 downregulated the expression of tumour necrosis factor-α, interleukin-6 and interleukin-10 in lipopolysaccharide-induced THP-1 cells. ApoE23 exhibits potential in future clinical applications.

Strategies to deliver peptide drugs to the brain

Neurological diseases such as neurodegeneration, pain, psychiatric disorders, stroke, and brain cancers would greatly benefit from the use of highly potent and specific peptide pharmaceuticals. Peptides are especially desirable because of their low inherent toxicity. The presence of the blood brain barrier (BBB), their short duration of action, and their need for parenteral administration limits their clinical use. However, over the past decade there have been significant advances in delivering peptides to the central nervous system. Angiopep peptides developed by Angiochem (Montreal, Canada), transferrin antibodies developed by ArmaGen (Santa Monica, USA), and cell penetrating peptides have all shown promise in delivering therapeutic peptides across the BBB after intravenous administration. Noninvasive methods of delivering peptides to the brain include the use of chitosan amphiphile nanoparticles for oral delivery and nose to brain strategies. The uptake of the chitosan amphiphile nanoparticles by the gastrointestinal epithelium is important for oral peptide delivery. Finally protecting peptides from plasma degradation is integral to the success of most of these peptide delivery strategies.

Apolipoprotein E and its mimetic peptide suppress Th1 and Th17 responses in experimental autoimmune encephalomyelitis

Apolipoprotein E (apoE) has been detected to possess anti-inflammatory properties that can contribute to protection against experimental autoimmune encephalomyelitis (EAE). However, its impact on Th1 and Th17 responses in EAE is unclear. In this study, we induced EAE in apoE-/- mice and wild-type mice. We observed that the absence of apoE resulted in the increased proportion of Th1 and Th17 cells in the spleens and brains, as well as up-regulated expressions of proinflammatory cytokines (IL-17, IFN-γ, TNF-α, IL-12, IL-1β and IL-6) and transcription factors (RORγt and T-bet) in the CNS. ApoE-/- mice also showed the increased release of proinflammatory cytokines by macrophages in vitro. In addition, we used a mimetic peptide of apoE, which mimic the functions of apoE except for lipid transport. ApoE mimetic peptide could reverse the above negative effect in EAE. Thus, apoE can modulate Th1 and Th17 responses, likely through its inhibitory effect on the secretion of cytokines by macrophages. Our result also suggests that apoE mimetic peptide might be developed into a therapeutic agent for multiple sclerosis.

Apolipoprotein E and Alzheimer disease: risk, mechanisms and therapy

Apolipoprotein E (Apo-E) is a major cholesterol carrier that supports lipid transport and injury repair in the brain. APOE polymorphic alleles are the main genetic determinants of Alzheimer disease (AD) risk: individuals carrying the ε4 allele are at increased risk of AD compared with those carrying the more common ε3 allele, whereas the ε2 allele decreases risk. Presence of the APOE ε4 allele is also associated with increased risk of cerebral amyloid angiopathy and age-related cognitive decline during normal ageing. Apo-E-lipoproteins bind to several cell-surface receptors to deliver lipids, and also to hydrophobic amyloid-β (Aβ) peptide, which is thought to initiate toxic events that lead to synaptic dysfunction and neurodegeneration in AD. Apo-E isoforms differentially regulate Aβ aggregation and clearance in the brain, and have distinct functions in regulating brain lipid transport, glucose metabolism, neuronal signalling, neuroinflammation, and mitochondrial function. In this Review, we describe current knowledge on Apo-E in the CNS, with a particular emphasis on the clinical and pathological features associated with carriers of different Apo-E isoforms. We also discuss Aβ-dependent and Aβ-independent mechanisms that link Apo-E4 status with AD risk, and consider how to design effective strategies for AD therapy by targeting Apo-E.

Apolipoprotein E Mimetic Promotes Functional and Histological Recovery in Lysolecithin-Induced Spinal Cord Demyelination in Mice

Objective

Considering demyelination is the pathological hallmark of multiple sclerosis (MS), reducing demyelination and/or promoting remyelination is a practical therapeutic strategy to improve functional recovery for MS. An apolipoprotein E (apoE)-mimetic peptide COG112 has previously demonstrated therapeutic efficacy on functional and histological recovery in a mouse experimental autoimmune encephalomyelitis (EAE) model of human MS. In the current study, we further investigated whether COG112 promotes remyelination and improves functional recovery in lysolecithin induced focal demyelination in the white matter of spinal cord in mice.

Methods

A focal demyelination model was created by stereotaxically injecting lysolecithin into the bilateral ventrolateral funiculus (VLF) of T8 and T9 mouse spinal cords. Immediately after lysolecithin injection mice were treated with COG112, prefix peptide control or vehicle control for 21 days. The locomotor function of the mice was measured by the beam walking test and Basso Mouse Scale (BMS) assessment. The nerve transmission of the VLF of mice was assessed in vivo by transcranial magnetic motor evoked potentials (tcMMEPs). The histological changes were also examined by by eriochrome cyanine staining, immunohistochemistry staining and electron microscopy (EM) method.

Results

The area of demyelination in the spinal cord was significantly reduced in the COG112 group. EM examination showed that treatment with COG112 increased the thickness of myelin sheaths and the numbers of surviving axons in the lesion epicenter. Locomotor function was improved in COG112 treated animals when measured by the beam walking test and BMS assessment compared to controls. TcMMEPs also demonstrated the COG112-mediated enhancement of amplitude of evoked responses.

Conclusion

The apoE-mimetic COG112 demonstrates a favorable combination of activities in suppressing inflammatory response, mitigating demyelination and in promoting remyelination and associated functional recovery in animal model of CNS demyelination. These data support that apoE-mimetic strategy may represent a promising therapy for MS and other demyelination disorders.

Paradoxical effects of apolipoprotein E on cognitive function and clinical progression in mice with experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is an inflammatory demyelinating disease characterized by sensory, motor, and cognitive impairments. Apolipoprotein E (apoE) plays an important role in cholesterol and lipid metabolism in the brain and in susceptibility to cognitive impairment and pathology following brain injury. Studies in mice with a mild form of experimental autoimmune encephalomyelitis (EAE), an MS animal model, support only protective roles for apoE in MS. We examined behavioral and cognitive changes prior to onset of clinical disease and the onset and progression of a more severe form of EAE in female Apoe(-/-) and C57Bl/6 wild-type mice. Apoe(-/-) mice had a later day of onset, a later day of peak symptoms and disease severity, and a lower cumulative disease index compared to wild type mice. Apoe(-/-) mice also showed decreased CD4+ cell invasion following EAE induction compared to wild type mice, and less spinal cord demyelination at 17 but not 30 days following EAE induction. In contrast, EAE-challenged Apoe(-/-) mice showed reduced exploratory activity, rotorod performance, and impaired contextual fear conditioning compared to wild type animals. These data indicate paradoxical effects of apoE on EAE-induced behavioral and cognitive changes and the onset and progression of clinical disease.

The apoE-mimetic peptide, COG1410, improves functional recovery in a murine model of intracerebral hemorrhage

BACKGROUND

Apolipoprotein E has previously been demonstrated to modulate acute brain injury responses, and administration of COG1410, an apoE-mimetic peptide derived from the receptor-binding region of apoE, improves outcome in preclinical models of acute neurological injury. In the current study, we sought to establish the optimal dose and timing of peptide administration associated with improved functional outcome in a murine model of intracerebral hemorrhage (ICH).

METHODS

Ten to twelve-week-old C57/BL6 male mice were injured by collagenase-induced ICH and randomly selected to receive either vehicle or one of four doses of COG1410 (0.5, 1, 2, or 4 mg/kg) via tail vein injection at 30 min after injury and then daily for 5 days. The injured mice were euthanized at various time points to assess inflammatory mediators, cerebral edema, and hematoma volume. Over the first 5 days following injury, vestibulomotor function was tested via Rotorod (RR) latency. After an optimal dose was demonstrated, a final cohort of animals was injured with ICH and randomly assigned to receive the first dose of COG1410 or vehicle at increasingly longer treatment initiation times after injury. The mice were then assessed for functional deficit via RR testing over the first 5 days following injury.

RESULTS

The mice receiving 2 mg/kg of COG1410 after injury demonstrated reduced functional deficit, decreased brain concentrations of inflammatory proteins, and less cerebral edema, although hematoma volume did not vary. The improved RR performance was maintained when peptide administration was delayed for up to 2 h after ICH.

CONCLUSIONS

COG1410 administered at a dose of 2 mg/kg within 2 h after injury improves functional recovery in a murine model of ICH.

Apolipoprotein E COG 133 mimetic peptide improves 5-fluorouracil-induced intestinal mucositis

Background

Intestinal mucositis is one of the major troublesome side effects of anticancer chemotherapy leading to poor patient compliance. In this study we addressed the role of the novel apolipoprotein E (ApoE) COG 133 mimetic peptide in 5-fluorouracil (5-FU)-challenged Swiss mice and IEC-6 cell monolayers. Experiments were also conducted in C57BL6J ApoE knock-out mice to assess the effects of apoE peptide treatment.

Methods

Experimental groups were as follows: unchallenged controls, 5-FU-challenged mice (450 mg/kg, i.p) with or without the ApoE peptide (0.3, 1, and 3 μM, given twice daily i.p. for 4 days). Mice were sacrificed 3 days after 5-FU challenge. Proximal small intestinal samples were harvested for molecular biology and histological processing. We conducted ELISA assays and RT-PCR to target IL-1β, TNF-α, IL-10, iNOS, and myeloperoxidase (MPO) to assess intestinal inflammation. Cell death and NF-κB assays were also conducted in apoE knock-out mice. In our in vitro models, IEC-6 cells were exposed to 1 mM of 5-FU in glutamine free media with or without the ApoE peptide (0.02, 0.2, 2, 5, 10, and 20 μM). We investigated IEC-6 cell proliferation and migration, 24 h after the 5-FU challenge. Additionally, apoptotic IEC-6 cells were measured by Tunel and flow cytometry. Equimolar doses of the ApoA-I (D4-F) peptide were also used in some experiments for comparative studies.

Results

Villus blunting and heavy inflammatory infiltrates were seen in the 5-FU-challenged group, findings that were partially ameliorated by the ApoE peptide. We found increased intestinal MPO and pro-inflammatory IL-1β and TNF-α levels, and TNF-α and iNOS transcripts, and reduction of IL-10 following 5-FU treatment, each of which were partially abrogated by the peptide. Improvements were also found in IEC-6 cell apoptosis and migration following ApoE and D-4F treatment.

Conclusion

Altogether, these findings suggest that the novel ApoE COG 133 mimetic peptide can reduce 5-FU-induced intestinal changes and potentially benefit mucositis.

Apolipoprotein E mimetics and cholesterol-lowering properties

Apolipoprotein E (apoE) is a ligand for clearance of lipoprotein remnants such as chylomicrons and very low-density lipoproteins. It has anti-atherogenic and anti-inflammatory properties. Therefore, there is extensive ongoing research to create peptides that can mimic properties of apoE. A number of synthetic peptides that encompass different regions of apoE have been studied for inhibiting inflammatory states, including Alzheimer disease. However, peptides that clear atherogenic lipoproteins, analogous to apoE, via enhanced hepatic uptake have not been previously reviewed. Toward this end, we describe the design and studies of a dual-domain apoE mimetic peptide, Ac-hE18A-NH(2). This peptide consists of residues 141-150, the putative receptor-binding region of human apoE, covalently linked to a well characterized class A amphipathic helix, 18A, which has no sequence homology to any other exchangeable apolipoprotein sequences. It demonstrates dramatic effects in reducing plasma cholesterol levels in dyslipidemic mouse and rabbit models. We discuss the scientific rationale and review the literature for the design and efficacy of the peptide. Analogous to apoE, this peptide bypasses the low-density lipoprotein receptor for the hepatic uptake of atherogenic lipoproteins via heparan sulfate proteoglycan (HSPG). ApoE mimetics such as Ac-hE18A-NH(2) may therefore restore or replace ligands in genetically induced hyperlipidemias to enable reduction in atherogenic lipoproteins via HSPG even in the absence of functional low-density lipoprotein receptors. Therefore, this and similar peptides may be useful in the treatment of dyslipidemic disorders such as familial hyperlipidemia and atherosclerosis.

APOE genotype alters glial activation and loss of synaptic markers in mice

The ε4 allele of the Apolipoprotein E (APOE) gene is the strongest genetic risk factor for late-onset Alzheimer's disease (AD), and affects clinical outcomes of chronic and acute brain damages. The mechanisms by which apoE affect diverse diseases and disorders may involve modulation of the glial response to various types of brain damage. We examined glial activation in a mouse model where each of the human APOE alleles are expressed under the endogenous mouse APOE promoter, as well as in APOE knock-out mice. APOE4 mice displayed increased glial activation in response to intracerebroventricular lipopolysaccharide (LPS) compared to APOE2 and APOE3 mice by several measures. There were higher levels of microglia/macrophage, astrocytes, and invading T-cells after LPS injection in APOE4 mice. APOE4 mice also displayed greater and more prolonged increases of cytokines (IL-1β, IL-6, TNF-α) than APOE2 and APOE3 mice. We found that APOE4 mice had greater synaptic protein loss after LPS injection, as measured by three markers: PSD-95, drebin, and synaptophysin. In all assays, APOE knock-out mice responded similar to APOE4 mice, suggesting that the apoE4 protein may lack anti-inflammatory characteristics of apoE2 and apoE3. Together, these findings demonstrate that APOE4 predisposes to inflammation, which could contribute to its association with Alzheimer's disease and other disorders.

A new recombinant human apolipoprotein E mimetic peptide with high-density lipoprotein binding and function enhancing activity

We generated a novel human apolipoprotein E (apoE)-mimetic peptide, designated EpK. EpK contains an N-terminal cysteine residue, a low-density lipoprotein receptor-binding fragment, a 6 × lysine linker and a lipid-binding fragment. The recombinant peptide was expressed in Escherichia coli, and purified with a chitin bead column followed by a Heparin Sepharose CL-6B column to yield pure peptide. EpK displayed high solubility in aqueous solution at neutral pH and adopted a low content of α-helical structure which was significantly increased in 2,2,2-trifluoroethanol or upon lipid binding. EpK retained similar 1,2-dimyristoyl(d54)-sn-glycero-3-phosphocholine binding activity as human apoE3 albeit with slower kinetics. Cell culture studies showed that EpK mediated cholesterol efflux from cholesterol-loaded primary murine macrophages with higher mass-based efficiency than human apoAI and human apoE3, and that EpK inhibited lipopolysaccharide (LPS)-induced proinflammatory cytokine expression in murine macrophages. When injected into apoE(-/-)mice, EpK predominantly associated with high-density lipoprotein (HDL), which was also shown in in vitro incubation experiments. Moreover, association of EpK with HDL enhanced the ability of HDL in mediating cholesterol efflux and suppressing LPS-induced proinflammatory cytokine expression in cholesterol-loaded human acute monocytic leukemia cell line (THP-1) macrophages. These data suggest that this novel recombinant apoE mimetic peptide enhances HDL function and harbors antiatherogenic potential.

SET oncoprotein overexpression in B-cell chronic lymphocytic leukemia and non-Hodgkin lymphoma: a predictor of aggressive disease and a new treatment target

B-cell chronic lymphocytic leukemia (CLL), an incurable leukemia, is characterized by defective apoptosis. We found that the SET oncoprotein, a potent inhibitor of the protein phosphatase 2A (PP2A) tumor suppressor, is overexpressed in primary CLL cells and B-cell non-Hodgkin lymphoma (NHL) cell line cells. In CLL, increased levels of SET correlated significantly with disease severity (shorter time to treatment and overall survival). We developed SET antagonist peptides that bound SET, increased cellular PP2A activity, decreased Mcl-1 expression, and displayed selective cytotoxicity for CLL and NHL cells in vitro. In addition, shRNA for SET was cytotoxic for NHL cells in vitro. The SET antagonist peptide COG449 inhibited growth of NHL tumor xenografts in mice. These data demonstrate that SET is a new treatment target in B-cell malignancies and that SET antagonists represent novel agents for treatment of CLL and NHL.

Low-density lipoprotein receptor-related protein 1 prevents early atherosclerosis by limiting lesional apoptosis and inflammatory Ly-6Chigh monocytosis: evidence that the effects are not apolipoprotein E dependent

BACKGROUND

We previously demonstrated that macrophage low-density lipoprotein receptor (LDLR)-related protein 1 (LRP1) deficiency increases atherosclerosis despite antiatherogenic changes including decreased uptake of remnants and increased secretion of apolipoprotein E (apoE). Thus, our objective was to determine whether the atheroprotective effects of LRP1 require interaction with apoE, one of its ligands with multiple beneficial effects.

METHODS AND RESULTS

We examined atherosclerosis development in mice with specific deletion of macrophage LRP1 (apoE(-/-) MΦLRP1(-/-)) and in LDLR(-/-) mice reconstituted with apoE(-/-) MΦLRP1(-/-) bone marrow. The combined absence of apoE and LRP1 promoted atherogenesis more than did macrophage apoE deletion alone in both apoE-producing LDLR(-/-) mice (+88%) and apoE(-/-) mice (+163%). The lesions of both mouse models with apoE(-/-) LRP1(-/-) macrophages had increased macrophage content. In vitro, apoE and LRP1 additively inhibit macrophage apoptosis. Furthermore, there was excessive accumulation of apoptotic cells in lesions of both LDLR(-/-) mice (+110%) and apoE(-/-) MΦLRP1(-/-) mice (+252%). The apoptotic cell accumulation was partially due to decreased efferocytosis as the ratio of free to cell-associated apoptotic nuclei was 3.5-fold higher in lesions of apoE(-/-) MΦLRP1(-/-) versus apoE(-/-) mice. Lesion necrosis was also increased (6 fold) in apoE(-/-) MΦLRP1(-/-) versus apoE(-/-) mice. Compared with apoE(-/-) mice, the spleens of apoE(-/-) MΦLRP1(-/-) mice contained 1.6- and 2.4-fold more total and Ly6-C(high) monocytes. Finally, there were 3.6- and 2.4-fold increases in Ly6-C(high) and CC-chemokine receptor 2-positive cells in lesions of apoE(-/-) MΦLRP1(-/-) versus apoE(-/-) mice, suggesting that accumulation of apoptotic cells enhances lesion development and macrophage content by promoting the recruitment of inflammatory monocytes.

CONCLUSION

Low-density lipoprotein receptor protein 1 exerts antiatherogenic effects via pathways independent of apoE involving macrophage apoptosis and monocyte recruitment.

Cross-talk between apolipoprotein E and cytokines

Apolipoprotein E (apoE) is a multifunctional glycosylated protein characterized by its wide tissue distribution. Despite its importance in lipid transport and atherosclerosis pathogenesis, apoE is associated with neurodegenerative disorders such as Alzheimer's disease (AD) and Parkinson disease, and autoimmune disorders such as multiple sclerosis and psoriasis. Among others, the role of apoE in modulating inflammation and oxidation is crucial in elucidating the risk factors of the above diseases since the function of apoE is closely linked with both proinflammatory and antiinflammatory cytokines. Moreover, apoE modulates inflammatory and immune responses in an isoform-dependent manner. Correspondingly, inflammatory cytokines can either upregulate or downregulate the production of apoE in various tissue types. However, studies on the interactions between apoE and cytokines occasionally yield conflicting results, highlighting the complex roles of apoE and cytokines in various disorders. The present paper summarizes the current knowledge about the cross-talk between apoE and cytokines, with emphasis on the effects of apoE on the Th1/Th2 balance.

Genetics for understanding and predicting clinical progression in multiple sclerosis

INTRODUCTION

Multiple sclerosis (MS) is a dys-immune disease of the central nervous system with highly variable and unpredictable long-term outcome.

STATE OF THE ART

In the early 1970s association between HLA alleles and MS was established. Very recently, the power of Genome Wide Association Studies (GWAS) enabled the identification of several loci involved in immune functions as genetic risk factors in MS. Recent data suggest that common genetic variations might modulate the clinical phenotype of MS through a regulation of key pathophysiological pathways.

PERSPECTIVES

Identification of modifier genes might offer an opportunity to explore new relevant therapeutic targets and early prognostic markers. To date, studies of modifier genes in MS are numerous but results are still unclear. This research field may now benefit from large cohorts of patients available for association studies.

CONCLUSION

In this context, we propose a review of epidemiological and association studies of genetic modifying effect in MS.

Targeting SET/I(2)PP2A oncoprotein functions as a multi-pathway strategy for cancer therapy

The SET oncoprotein participates in cancer progression by affecting multiple cellular processes, inhibiting the tumor suppressor protein phosphatase 2A (PP2A), and inhibiting the metastasis suppressor nm23-H1. On the basis of these multiple activities, we hypothesized that targeted inhibition of SET would have multiple discrete and measurable effects on cancer cells. Here, the effects of inhibiting SET oncoprotein function on intracellular signaling and proliferation of human cancer cell lines was investigated. We observed the effects of COG112, a novel SET interacting peptide, on PP2A activity, Akt signaling, nm23-H1 activity and cellular migration/invasion in human U87 glioblastoma and MDA-MB-231 breast adenocarcinoma cancer cell lines. We found that COG112 interacted with SET protein and inhibited the association between SET and PP2A catalytic subunit (PP2A-c) and nm23-H1. The interaction between COG112 and SET caused PP2A phosphatase and nm23-H1 exonuclease activities to increase. COG112-mediated increases in PP2A activity resulted in the inhibition of Akt signaling and cellular proliferation. Additionally, COG112 inhibited SET association with Ras-related C(3) botulinum toxin substrate 1 (Rac1), leading to decreased cellular migration and invasion. COG112 treatment releases the SET-mediated inhibition of the tumor suppressor PP2A, as well as the metastasis suppressor nm23-H1. These results establish SET as a novel molecular target and that the inhibition of SET may have beneficial effects in cancer chemotherapy.