P3387Cholesterol crystals in superficial plaque layer detected by optical coherence tomography as a new morphological feature for plaque rupture

Background

While plaque rupture (PR) is the leading cause of acute myocardial infarction (AMI), other etiologies are also involved in the onset of AMI. Cholesterol crystals (CCs) are usually present abundantly in atherosclerotic plaques, especially in the culprit site of AMI. However, the relationship between in vivo CCs and PR is unclear. Optical coherence tomography (OCT) is a high-resolution imaging technique that allows for the in vivo identification of various plaque characteristics including PR and CCs.

Purpose

The aim of this study was to investigate prevalence and distribution of CCs between patients with AMI with PR, AMI without PR, and SAP.

Method

This study consisted of 146 patients with coronary artery disease (AMI with PR; n=64, AMI without PR; n=41, and SAP; n=41) who underwent OCT prior to percutaneous coronary intervention. Plaque characteristics in OCT images were assessed according to the consensus document. We classified the distribution of CCs as follows; superficial type CCs were defined by any of the CCs invading the fibrous cap and remaining CCs as deep type CCs.

Result

There was no statistical difference in clinical characteristics among the three groups. The % diameter stenosis was significantly smaller in the SAP group than others (AMI with PR 91±12% vs. AMI without PR 86±13% vs. SAP 65±9%, p<0.001). The prevalence of CCs was significantly higher in the AMI with PR group than others (AMI with PR 78% vs. AMI without PR 41% vs. SAP 39%, p<0.001). The prevalence of superficial type CCs was significantly different among the groups (AMI with PR 72% vs. AMI without PR 24% vs. SAP 7%, p<0.001). Multivariable logistic analysis demonstrated that lipid plaque (OR 84.5, 95% CI [6.30–11332.33], p<0.001) and superficial type CC (OR 9.5, 95% CI [2.61–34.89], p<0.001) were independent predictors of PR.

Conclusion

Plaque with CCs invading the fibrous cap is frequently associated with PR in patients with AMI, suggesting. In vivo CC detection is a new morphological feature for plaque rupture.

Acknowledgement/Funding

This study was supported by a grant from JSPS KAKENHI (17K09557).

102Diagnosis of coronary plaque rupture, plaque erosion, and calcified nodule by using near-infrared spectroscopy intravascular ultrasound

Objectives

This study sought to investigate the ability of near-infrared spectroscopy intravascular ultrasound (NIRS-IVUS) to differentiate among plaque rupture (PR), plaque erosion (PE), and calcified nodule (CN) in acute myocardial infarction (AMI) using an optical coherence tomography (OCT) diagnosis as a reference standard.

Background

In vivo, precise differentiation among PR, PE and CN is a major challenge for intravascular imaging.

Methods

The study enrolled 156 AMI patients who had a de novo culprit lesion in a native coronary artery. The culprit lesions were assessed by both NIRS-IVUS and OCT.

Results

OCT identified 112 PR, 29 PE, and 15 CN. IVUS-detected plaque ulceration showed a high specificity (100%) to identify OCT-PR although the sensitivity (62%) was intermediate. IVUS-detected convex calcium showed a high sensitivity (93%) and specificity (100%) to identify OCT-CN. In NIRS, the maximum lipid core burden index in 4 mm (maxLCBI4mm) was greatest in OCT-PR (values are median [interquartile range]) (671 [530 to 853]), followed by OCT-CN (355 [303 to 432]) and OCT-PE (283 [89 to 357]) (p<0.001). MaxLCBI4mm of <422 was the best cut-off to discriminate OCT-PE from OCT-PR and OCT-CN. The NIRS-IVUS classification algorithm using plaque ulceration, convex calcium, and maxLCBI4mm <422 showed a sensitivity and specificity of 96% and 95% for identifying OCT-PR, 93% and 95% for OCT-PE, and 93% and 100% for OCT-CN, respectively.

NIRS-IVUS classification algorism

Conclusion

Lipid component assessed by NIRS-IVUS was different among OCT-PR, OCT-PE and OCT-CN. The NIRS-IVUS classification algorism was highly sensitive and specific for differentiating these unstable lesion types in AMI.

Acknowledgement/Funding

None

Signal amplification in flow cytometry for cell surface antigen analysis

Signal enhancing systems have been introduced to enable detection of cell surface antigens by flow cytometry. Cell surface antigens are important targets that describe the function and lineage of cells. Although flow cytometry is an effective tool for analysing cell surface antigens, this technique has poor sensitivity, which prohibits the detection of many important antigens on cell membranes. Thus, signal amplification is essential for developing practical tools for evaluating cell surface antigens by flow cytometry. Using a bright fluorophore or fluorescent polymer incorporated into antibodies is a straightforward strategy to improve flow cytometry sensitivity but may affect the functional characteristics of the labelled antibody. In contrast, enzymatic signal amplification is a more practical and efficient strategy to improve sensitivity that should not affect antibody activity. Although enzymatic signal amplification still has a number of drawbacks, this approach is a promising strategy to analyse cell surface antigens.

Injectable Polypeptide Hydrogel Depot System for Assessment of the Immune Response-Inducing Efficacy of Sustained Antigen Release Alone

Vaccines typically contain an antigen, delivery system (vehicle), and adjuvant, all of which contribute to inducing a potent immune response. Consequently, design of new vaccines is difficult, because the contributions and interactions of these components are difficult to distinguish. Here, it is aimed to develop an easy-to-use, non-immunogenic, injectable depot system for sustained antigen release that will be suitable for assessing the efficacy of prolonged antigen exposure per se for inducing an immune response. This should mimic real-life infections. Recombinant elastin-like polypeptides with periodic cysteine residues (cELPs) are selected, which reportedly show little or no immunogenicity, as carriers and tetanus toxoid (Ttd) as an antigen. After subcutaneous injection of the mixture, cELP rapidly forms a disulfide cross-linked hydrogel in situ, within which Ttd is physically incorporated, affording a biodegradable antigen depot. A series of Ttd-containing hydrogels is examined. A single injection induces high levels of tetanus antibody with high avidity for at least 20 weeks in mice. The chain length of cELP proves critical, whereas differences in hydrophobicity has little effect, although hydrophilic cELPs are more rapidly biodegraded. This system's ability to distinguish the contribution of sustained antigen release to antibody induction should be helpful for rational design of next-generation vaccines.

Two Cases of Equine Multinodular Pulmonary Fibrosis in Japan

Equine multinodular pulmonary fibrosis (EMPF) is a recently described form of interstitial pneumonia associated with equine herpesvirus type 5 (EHV-5). This disease has been reported in North and South America, Europe and Oceania but not, to our knowledge, in horses in Japan. We diagnosed EMPF in two Thoroughbred horses in Japan on the basis of gross and histopathological findings. In both cases, significant gross lesions, restricted to the lungs, consisted of numerous firm and coalescing nodules widely distributed throughout the lung. The nodules were <3 cm in diameter and pale white to tan in colour. Microscopically, they showed severe interstitial fibrosis and infiltration of macrophages, neutrophils, lymphocytes and a few eosinophils. The residual alveoli were lined by cuboidal epithelial cells (type II pneumocytes) and filled with many macrophages, which rarely displayed oval eosinophilic to amphophilic intranuclear inclusion bodies. Polymerase chain reaction and sequence analyses identified the glycoprotein H gene of EHV-5, and in-situ hybridization detected EHV-5 in the alveolar macrophages in the lesions. In one case, electron microscopy revealed herpesvirus-like particles and EHV-5 was isolated from pulmonary lesions.

Rapid and continuous accumulation of nitric oxide-releasing liposomes in tumors to augment the enhanced permeability and retention (EPR) effect

The modulation of blood flow to tumors is a prominent strategy for improving the tumor accumulation of nanomedicines, resulting from the enhanced permeability and retention (EPR) effect. We previously reported a promising EPR enhancer-a nitric oxide (NO) donor-containing liposome (NO-LP)-which showed enhanced accumulation in tumor tissue. Herein, we study NO-LP in greater detail to clarify its practical use as an EPR enhancer. NO-LP was found to have advantages as a NO donor, including the ability to maintain NO donation over long periods of time, and a constant rate of NO-release irrespective of the environmental pH. NO-LP showed rapid accumulation in tumor tissue after injection (1 h), and then accumulation was continuously enhanced until 48 h. Enhanced NO-LP accumulation was observed specifically in tumor, while the accumulation in other organs remained relatively unchanged. The results obtained show the promising features of NO-LP as an EPR enhancer.

Folate receptor-specific cell-cell adhesion by using a folate-modified peptide-based anchor

We report here a folate-modified membrane anchor for cell surface modification to induce cell adhesion to target cells. The membrane anchor region, which was consisted of cationic lysine residues and palmitoyl group-modified residues, was modified with folate through an oligoethlene glycol linker. The peptide anchor was modified on to the cell membrane by using β-cyclodextrin as a solubilizer of the peptide anchor. After modification, the peptide anchor disappeared from the cell membrane via endocytotic uptake or dissociation from the cell membrane. However, the endocytosed peptide was represented on the cell surface via recycling endosome pathway. The obtained folate-modified cells successfully adhered on to target cells which expressed folate receptor α via ligand-receptor specific interaction and adhesion continued at least 4 hours.

Regulation of inflammatory response of macrophages and induction of regulatory T cells by using retinoic acid-loaded nanostructured lipid carrier

Immunomodulatory function of all-trans retinoic acid (ATRA) has been gathering much attention for the therapy of autoimmune diseases. ATRA is a chemically unstable molecule which requires proper formulation for targeted delivery. Here we examined nanostructured lipid carrier (NLC) for the formulation of ATRA. NLC is a representative nanoparticle formulation especially suited for oral delivery. We established the preparation procedures of ATRA-containing NLC (NLC-RA) which minimizes the degradation of ATRA during the preparation process. NLC-RA thus obtained was taken up by macrophages and induced anti-inflammatory response via suppressing NF-κB signaling as well as via enhancing the production of anti-inflammatory cytokines. Moreover, NLC-RA enhanced differentiation of naïve T cells to regulatory T cells in the co-culture system with dendritic cells. These results suggest that NLC-RA is a promising alternative therapy for the autoimmune diseases especially intestinal bowel disease.

Preparation of Complexes between Ovalbumin Nanoparticles and Retinoic Acid for Efficient Induction of Tolerogenic Dendritic Cells

The induction of antigen-specific immunotolerance has been gathering attention concerning the therapy of allergy and autoimmune diseases. Tolerogenic dendritic cells (tDCs) play crucial roles in immunotolerance therapy because they induce anergic responses for auto-reactive helper T cells, and also enhance differentiation to regulatory T cells to maintain tolerance against auto-antigens. All-trans retinoic acid (ATRA) is one of the representative molecules used to induce tDCs. We have proposed a simple formulation of ovalbumin nanoparticles complexed with ATRA (OVA/RA NPs). OVA/RA NPs were taken up by DCs and successfully induced phenotypes of tDCs.

Therapeutic effect of vitamin D3-containing nanostructured lipid carriers on inflammatory bowel disease

The active form of vitamin D₃, 1,25(OH)₂D₃ has been found to exert multiple effects on the suppression of progression of inflammatory bowel disease (IBD). Vitamin D₃ has been gathering attention as a therapy for IBD. However, the clinical trials conducted to date revealed that a relatively high dosage of vitamin D₃ was required to see a significant therapeutic effect. Thus, effective formulation and delivery of vitamin D₃ to colonic inflammatory lesions will be required. Herein we describe the preparation of a nanostructured lipid carrier (NLC) for the encapsulation of 1,25(OH)₂D₃ for colonic delivery via oral administration. The optimized fabrication procedure enabled the incorporation of 1,25(OH)₂D₃ in the NLC by minimizing the destruction of chemically unstable 1,25(OH)₂D₃. The obtained NLCs orally delivered 1,25(OH)₂D₃ to the colon in mice and maintained a high concentration of 1,25(OH)₂D₃ in the colonic tissue for at least 12 h. The NLC showed multiple effects on the suppression of symptoms of colitis induced by dextran sodium sulfate, namely maintaining crypt structure, reducing the tissue concentration of inflammatory cytokines, suppressing the infiltration of polymorphonuclear leukocytes, and augmenting anti-inflammatory CX₃CR1^high macrophages. Our NLCs containing 1,25(OH)₂D₃ may be an alternative treatment for IBD therapy.

A peptide inhibitor of antibody-dependent cell-mediated cytotoxicity against EGFR/folate receptor-α double positive cells

Antibody-dependent cell-mediated cytotoxicity (ADCC) is caused by natural killer (NK) cells upon recognition of antigen-bound IgG via FcγRIIIa. This mechanism is crucial for cytolysis of pathogen-infected cells and monoclonal antibody (mAb)-mediated elimination of cancer cells. However, there is concern that mAb-based cancer therapy induces ADCC against non-target cells expressing antigens. To date, no strategy has been reported to enhance the selectivity of ADCC to protect non-target cells expressing antigens. Here, we introduce a model inhibitor which specifically blocks ADCC of anti-EGFR mAbs towards EGFR/folate receptor α (FRα) double positive cells. This inhibitor recruits mAbs on the FRα of the cell surface independent of Fab antigen recognition. The resulting ternary and/or quaternary complexes formed on the cell surface suppress signal transduction of FcγRIIIa in NK cells, consequently leading to more specific ADCC.

Ligand-Mediated Coating of Liposomes with Human Serum Albumin

Coating liposome surfaces with human serum albumin (HSA) can improve the colloidal stability and prevent opsonization. HSA coating via specific binding with alkyl ligands is promising because although the ligand-mediated coating is relatively stable it can spontaneously exchange with fresh HSA. However, to achieve surface coating with HSA, multiple hydrophobic ligands must be exposed to an aqueous medium prior to binding with HSA. This presents a challenge, as hydrophobic ligands tend to be buried in the liposomal membrane. Here we present the first HSA modification of liposome surfaces via alkyl ligands. We found that a relatively short alkyl ligand, or a long alkyl ligand with a terminal carboxylate, could be exposed on the liposome surface without causing aggregation of the liposomes and these ligands could subsequently bind HSA. The resulting HSA-coated liposomes were as inert as conventional PEGylated liposomes in terms of macrophage recognition.

Intraoperative 5-aminolevulinic acid-induced photodynamic diagnosis of metastatic brain tumors with histopathological analysis

BACKGROUND

Fluorescence-guided surgery using 5-aminolevulinic acid (5-ALA) is a promising real-time navigation method in the surgical resection of malignant gliomas. In order to determine whether this method is applicable to metastatic brain tumors, we evaluated the usefulness of intraoperative fluorescence patterns and histopathological features in patients with metastatic brain tumors.

METHODS

We retrospectively reviewed the cases of 16 patients with metastatic brain tumors who underwent intraoperative 5-ALA fluorescence-guided resection. Patients were given 20 mg/kg of 5-ALA orally 2 h prior to the surgery. High-powered excitation illumination and a low-pass filter (420, 450, or 500 nm) were used to visualize the fluorescence of protoporphyrin IX (PpIX), the 5-ALA metabolite. We evaluated the relationships between the fluorescence and histopathological findings in both tumoral and peritumoral brain tissue.

RESULTS

Tumoral PpIX fluorescence was seen in only 5 patients (31%); in the remaining 11 patients (69%), there was no fluorescence in the tumor bulk itself. In 14 patients (86%), vague fluorescence was seen in peritumoral brain tissue, at a thickness of 2-6 mm. The histopathological examination found cancer cell invasion of adjacent brain tissue in 75% of patients (12/16), at a mean ± SD depth of 1.4 ± 1.0 mm (range 0.2-3.4 mm) from the microscopic border of the tumor. There was a moderate correlation between vague fluorescence in adjacent brain tissue and the depth of cancer cell invasion (P = 0.004).

CONCLUSION

Peritumoral fluorescence may be a good intraoperative indicator of tumor extent, preceding more complete microscopic gross total resection.

TRIAL REGISTRATION

Institutional Review Board of Osaka Medical College No. 42, registered February 17, 1998, and No. 300, registered April 1, 2008. They were retrospectively registered.

Synergic modulation of the inflammatory state of macrophages utilizing anti-oxidant and phosphatidylserine-containing polymer-lipid hybrid nanoparticles

Inflammatory activation of macrophages is a key factor in chronic inflammatory diseases such as ulcerative colitis. The excessive production of reactive oxygen species (ROS)/reactive nitrogen species (RNS) by macrophages causes oxidative stress during the inflammatory response and exaggerates inflammatory lesions in ulcerative colitis. Inhibition of the inflammatory activation of macrophages is a promising treatment for chronic inflammatory diseases. Here, we prepared self-filling polymer-lipid hybrid nanoparticles (PST-PLNPs) consisting of poly dl-lactic acid as a hydrophobic biodegradable polymer core encapsulating α-tocopherol (T) and phosphatidylserine (PS) both on the surface and interior of the particle. We confirmed the anti-inflammatory response of these hybrid nanoparticles in activated murine macrophages. PS has anti-inflammatory effects on macrophages by modulating the macrophage phenotype, while α-tocopherol is an antioxidant that neutralizes ROS. We found that PS-containing (PS-PLNPs) and PS plus α-tocopherol-containing (PST-PLNPs) polymer-lipid hybrid nanoparticles significantly increased the viability of lipopolysaccharide (LPS)-treated macrophages compared with phosphatidylcholine-containing PLNPs. PST-PLNPs had a better effect than PS-PLNPs, which was attributed to the synergy between PS and α-tocopherol. This synergic action of PST-PLNPs reduced NO and pro-inflammatory cytokine (IL-6) production and increased anti-inflammatory cytokine (TGF-β1) production when incubated with activated macrophages. Thus, these self-filling biodegradable polymer-lipid hybrid nanoparticles (PST-PLNPs) containing anti-oxidant and anti-inflammatory molecules might be potential alternative drug carriers to liposomes and polymeric nanoparticles for the treatment of chronic inflammatory diseases such as ulcerative colitis.

Design of a ligand for cancer imaging with long blood circulation and an enhanced accumulation ability in tumors

The use of imaging agents to visualize tumor cells is an advantageous technique to achieve a more efficient intraoperative diagnosis and effective debulking operations. Targeting of these agents to certain receptors that are overexpressed in cancer cells, such as the folate receptor, aids in tumor targeting. Several imaging probes have been developed using this strategy. However, these ligand-targeting cancer imaging probes are rapidly cleared during systemic delivery due to their small size, which compromises their biodistribution and circulation. Improving the detection of cancer requires higher accumulation and effective retention activities of imaging probes. Here we developed a new design for a folate-fluorophore conjugate that is modified with palmitoyl. Palmitic acid has a strong binding affinity with human serum albumin (HSA), which has the ability to form non-covalent host-guest complexes and has a blood half-life of 19 days. In this strategy, HSA is expected to serve as an endogenous nanocarrier for the designed probe in blood circulation. We hypothesized that via a reversible interaction with HSA, this simple palmitoyl modification on a folate-fluorophore conjugate can induce long blood circulation of the probe. Our folate-targeted probe could show longer blood circulation compared to the probe which lacks palmitoyl.