ABSTRACT
PEGylated lipid protein immunogens delivered intranasally to mice and macaques drive production of IgG and IgA antibodies at other mucosal sites (Hartwell et al.).
Subject(s)
Immunity, Mucosal , Immunoglobulin A , Animals , MiceABSTRACT
BACKGROUND: The hydrophobic pocket (HP) of HIV-1 glycoprotein-41 ectodomain is defined by two chains of the N-heptad repeat trimer, within the protein-protein interface that mediates 6HB formation. It is a potential target for inhibitors of viral fusion, but its hydrophobic nature and proximity to membrane in situ has precluded ready analysis of inhibitor interactions. METHODS: We evaluated the sensitivity of 19F NMR and fluorescence for detecting peptide and small molecule binding to the HP and explored the effect of non-denaturing detergent or phospholipid as cosolvents and potential mimics of the membrane environment surrounding gp41. RESULTS: Chemical shifts of aromatic fluorines were found to be sensitive to changes in the hydrogen bonding network that occurred when inhibitors transitioned from solvent into the HP or into ordered detergent micelles. Fluorescence intensities and emission maxima of autofluorescent compounds responded to changes in the local environment. CONCLUSIONS: Gp41 - ligand binding occurred under all conditions, but was diminished in the presence of detergents. NMR and fluorescence studies revealed that dodecylphosphocholine (DPC) was a poor substitute for membrane in this system, while liposomes could mimic the membrane surroundings. GENERAL SIGNIFICANCE: Our findings suggest that development of high potency small molecule binders to the HP may be frustrated by competition between binding to the HP and binding to the bilayer membrane.
Subject(s)
Detergents/metabolism , HIV Envelope Protein gp41/metabolism , HIV-1/metabolism , Phospholipids/metabolism , Small Molecule Libraries/metabolism , Cholesterol/metabolism , HIV Envelope Protein gp41/chemistry , HIV Infections/drug therapy , HIV Infections/virology , HIV-1/chemistry , Humans , Lipid Bilayers/metabolism , Liposomes/metabolism , Models, Molecular , Protein Binding , Protein UnfoldingABSTRACT
Versatile and precise genome modifications are needed to create a wider range of adoptive cellular therapies1-5. Here we report two improvements that increase the efficiency of CRISPR-Cas9-based genome editing in clinically relevant primary cell types. Truncated Cas9 target sequences (tCTSs) added at the ends of the homology-directed repair (HDR) template interact with Cas9 ribonucleoproteins (RNPs) to shuttle the template to the nucleus, enhancing HDR efficiency approximately two- to fourfold. Furthermore, stabilizing Cas9 RNPs into nanoparticles with polyglutamic acid further improves editing efficiency by approximately twofold, reduces toxicity, and enables lyophilized storage without loss of activity. Combining the two improvements increases gene targeting efficiency even at reduced HDR template doses, yielding approximately two to six times as many viable edited cells across multiple genomic loci in diverse cell types, such as bulk (CD3+) T cells, CD8+ T cells, CD4+ T cells, regulatory T cells (Tregs), γδ T cells, B cells, natural killer cells, and primary and induced pluripotent stem cell-derived6 hematopoietic stem progenitor cells (HSPCs).
Subject(s)
CRISPR-Associated Protein 9/metabolism , Polymers/chemistry , Adult , Gene Editing , Humans , Nanoparticles/chemistry , Protein Stability , RNA, Guide, Kinetoplastida/metabolismABSTRACT
Branched-chain amino acid (BCAA; valine, leucine and isoleucine) supplementation is often beneficial to energy expenditure; however, increased circulating levels of BCAA are linked to obesity and diabetes. The mechanisms of this paradox remain unclear. Here we report that, on cold exposure, brown adipose tissue (BAT) actively utilizes BCAA in the mitochondria for thermogenesis and promotes systemic BCAA clearance in mice and humans. In turn, a BAT-specific defect in BCAA catabolism attenuates systemic BCAA clearance, BAT fuel oxidation and thermogenesis, leading to diet-induced obesity and glucose intolerance. Mechanistically, active BCAA catabolism in BAT is mediated by SLC25A44, which transports BCAAs into mitochondria. Our results suggest that BAT serves as a key metabolic filter that controls BCAA clearance via SLC25A44, thereby contributing to the improvement of metabolic health.
Subject(s)
Adipose Tissue, Brown/metabolism , Amino Acid Transport Systems/metabolism , Amino Acids, Branched-Chain/metabolism , Energy Metabolism , Homeostasis , Mitochondrial Proteins/metabolism , Solute Carrier Proteins/metabolism , Thermogenesis , Adipose Tissue, Brown/cytology , Animals , Cold Temperature , Glucose Intolerance/metabolism , Humans , Male , Mice , Mitochondria/metabolism , Obesity/metabolismABSTRACT
Poor solute transport through the cartilage endplate (CEP) impairs disc nutrition and could be a key factor that limits the success of intradiscal biologic therapies. Here we demonstrate that treating the CEP with matrix metalloproteinase-8 (MMP-8) reduces the matrix constituents that impede solute uptake and thereby improves nutrient diffusion. Human CEP tissues harvested from four fresh cadaveric lumbar spines (age range: 38-66 years old) were treated with MMP-8. Treatment caused a dose-dependent reduction in sGAG, localized reductions to the amount of collagen, and alterations to collagen structure. These matrix modifications corresponded with 16-24% increases in the uptake of a small solute (376 Da). Interestingly, the effects of MMP-8 treatment depended on the extent of non-enzymatic glycation: treated CEPs with high concentrations of advanced glycation end products (AGEs) exhibited the lowest uptake compared to treated CEPs with low concentrations of AGEs. Moreover, AGE concentrations were donor-specific, and the donor tissues with the highest AGE concentrations appeared to have lower uptake than would be expected based on the initial amounts of collagen and sGAG. Finally, increasing solute uptake in the CEP improved cell viability inside diffusion chambers, which supports the nutritional relevance of enhancing the transport properties of the CEP. Taken together, our results provide new insights and in vitro proof-of-concept for a treatment approach that could improve disc nutrition for biologic therapy: specifically, matrix reduction by MMP-8 can enhance solute uptake and nutrient diffusion through the CEP, and AGE concentration appears to be an important, patient-specific factor that influences the efficacy of this approach.
Subject(s)
Cartilage/drug effects , Cartilage/metabolism , Intervertebral Disc/drug effects , Intervertebral Disc/metabolism , Matrix Metalloproteinase 8/metabolism , Matrix Metalloproteinase 8/pharmacology , Adult , Aged , Biological Transport/drug effects , Cartilage/cytology , Cell Survival , Collagen/metabolism , Extracellular Matrix/drug effects , Extracellular Matrix/metabolism , Humans , In Vitro Techniques , Intervertebral Disc Degeneration/drug therapy , Intervertebral Disc Degeneration/metabolism , Middle Aged , Recombinant Proteins/metabolism , Recombinant Proteins/pharmacologyABSTRACT
AmBisome® is a liposomal formulation of amphotericin B (Amp B), a complex parenteral antifungal product with no US FDA approved generic version available to date. For generic Amp B liposomal product development, examination of the drug release profile is important for product quality control and analytical comparability evaluation with the reference listed drug. Yet, there is no standardized in vitro drug release (IVR) assay currently available for Amp B liposomes. In this study, we describe the development of a USP-4 apparatus-based IVR assay capable of discriminating liposomal Amp B formulations based on the drug release profile. The goal of the IVR assay development was to identify release media compositions and assay temperatures capable of facilitating 70-100% of drug release from AmBisome® in 24â¯h without Amp B precipitation or disruption of liposome structure. We found that an addition of 5% w/v of γ-cyclodextrin to the release media of 5% sucrose, 10â¯mM HEPES, and 0.01% NaN3 (pHâ¯=â¯7.4) prevented Amp B precipitation and facilitated drug release. Increased IVR assay temperature led to increased drug release rate, and 55⯰C was selected as the highest temperature that induced drug release close to our target without causing product precipitation. The developed IVR assay was used to discriminate between drug release rates from AmBisome® and micellar Amp B products like Fungizone® and Fungcosome. The IVR assay was also capable of discriminating between Amp B liposomes with the same composition as AmBisome® but prepared by either extrusion or homogenization processes, both of which resulted in measurable liposomal particle size heterogeneity and Amp B concentration differences. Finally, the USP-4 IVR assay was used to compare Amp B release profiles between AmBisome® and two generic products approved in India, Amphonex® (Bharat Serums and Vaccines Ltd.) (f2â¯=â¯66.3) and Phosome® (Cipla Ltd.) (f2â¯=â¯55.4). Taken together, the developed USP-4 IVR assay can be a useful tool for drug release profile characterization in generic liposomal Amp B formulation development.
Subject(s)
Amphotericin B/chemistry , Antifungal Agents/chemistry , Chemistry, Pharmaceutical/instrumentation , Drug Development/instrumentation , Drug Liberation , Chemistry, Pharmaceutical/methods , Drug Development/methods , Particle SizeABSTRACT
Correction for 'Sterol-modified PEG lipids: alteration of the bilayer anchoring moiety has an unexpected effect on liposome circulation' by Aaron Dolor et al., Chem. Commun., 2018, 54, 11949-11952.
ABSTRACT
We synthesized and characterized two novel sterol-anchored polyethylene glycols (PEG) as potential alternatives to conventional phosphatidylethanolamine-PEGs. Liposomes containing the dicholesterol anchored PEG at 5 mole percent exhibit canonical PEGgylated-liposome behaviors including retention of encapsulated small molecules, low serum protein adsorption, and reduced cellular uptake yet they do not exhibit long circulation.
Subject(s)
Lipid Bilayers/chemistry , Liposomes/metabolism , Polyethylene Glycols/chemistry , Lipids/chemistry , Liposomes/chemistry , Microscopy, Electron, Transmission , Molecular Structure , Sterols/chemistryABSTRACT
Collagen and hyaluronan are the most abundant components of the extracellular matrix (ECM) and their overexpression in tumors is linked to increased tumor growth and metastasis. These ECM components contribute to a protective tumor microenvironment by supporting a high interstitial fluid pressure and creating a tortuous setting for the convection and diffusion of chemotherapeutic small molecules, antibodies, and nanoparticles in the tumor interstitial space. This review focuses on the research efforts to deplete extracellular collagen with collagenases to normalize the tumor microenvironment. Although collagen synthesis inhibitors are in clinical development, the use of collagenases is contentious and clinically untested in cancer patients. Pretreatment of murine tumors with collagenases increased drug uptake and diffusion 2-10-fold. This modest improvement resulted in decreased tumor growth, but the benefits of collagenase treatment are confounded by risks of toxicity from collagen breakdown in healthy tissues. In this review, we evaluate the published in vitro and in vivo benefits and limitations of collagenase treatment to improve drug delivery.
Subject(s)
Antineoplastic Agents/administration & dosage , Collagenases/pharmacology , Drug Delivery Systems/methods , Extracellular Matrix/drug effects , Neoplasms/drug therapy , Animals , Cell Line, Tumor , Collagen/metabolism , Collagen/toxicity , Disease Models, Animal , Extracellular Matrix/metabolism , Humans , Hyaluronic Acid/metabolism , Neoplasms/pathologyABSTRACT
We report here the first exploration of the nature of the hydrophobic region of bilayer membranes formed from sterol-modified phospholipids [Huang, Z.; Szoka, F. C., Sterol-Modified Phospholipids: Cholesterol and Phospholipid Chimeras with Improved Biomembrane Properties. J. Am. Chem. Soc. 2008, 130 (46), 15702-15712] & [Ding, J.; Starling, A. P.; East, J. M.; Lee, A. G., Binding Sites for Cholesterol on Ca(2+)-ATPase Studied by Using a Cholesterol-Containing Phospholipid. Biochemistry 1994, 33 (16), 4974-4979]. Using 2H NMR spectroscopy, we present our results for the phase behavior and acyl chain ordering of multilamellar vesicles (MLVs) of a sterol-modified phospholipid, 1-cholesterylhemisuccinoyl-2-palmitoyl(d31)-sn-glycero-3-phosphocholine (hereafter referred to as CholPPC-d31). We compared our results with the conformational order induced by cholesterol at various concentrations in 1-palmitoyl,2-palmitoyl(d31)-sn-glycero-3-phosphocholine (DPPC-d31)/cholesterol membranes. On the basis of the existing literature [Foglia, F.; Barlow, D. J.; Szoka, F. C.; Huang, Z.; Rogers, S. E.; Lawrence, M. J., Structural Studies of the Monolayers and Bilayers Formed by a Novel Cholesterol-Phospholipid Chimera. Langmuir 2011, 27 (13), 8275-8281], we expected to find that the deuterated palmitoyl chain in CholPPC-d31 membranes had an order parameter profile similar to the deuterated palmitoyl chain of sn-2 labeled DPPC-d31 in MLVs of a mixture of DPPC-d31 with 40 mol % unconstrained cholesterol. Our data indicate that the ordering ability of cholesterol in CholPPC is significantly reduced compared to free cholesterol in DPPC. This result emphasizes that cholesterol molecules must be free to move in the bilayers to reach their maximum ordering ability. In other words, when compared to unconstrained cholesterol, the constrained cholesterol moiety in CholPPC causes nonoptimal chain packing.
Subject(s)
Cholesterol/chemistry , Deuterium , Lipid Bilayers , Magnetic Resonance Spectroscopy , PhospholipidsABSTRACT
New methods to produce large numbers of myeloid progenitor cells, precursors to macrophages (MΦs), by maintaining Hoxb8 transcription factor activity1 has reinvigorated interest in MΦ cell therapies. We generated Hoxb8-dependent myeloid progenitors (HDPs) by transducing lineage-negative bone marrow cells with a constitutively expressed Hoxb8 flanked by loxP. HDPs proliferate indefinitely and differentiate into MΦ when Hoxb8 is removed by a tamoxifen-inducible Cre. We genetically modified HDPs with a constitutively active GMCSF receptor and the tamoxifen-induced transcription factor IRF8, which we have termed "HDP-on." The HDP-on proliferates without GMCSF and differentiates into the MΦ upon exposure to tamoxifen and ruxolitinib (GMCSF inhibitor via JAK1/2 blockade). We quantified the biodistribution of HDPs transplanted via intraperitoneal injection into immunodeficient NCG mice with a luciferase reporter; HDPs are detected for 14 days in the peritoneal cavity, liver, spleen, kidney, bone marrow, brain, lung, heart, and blood. In immunocompetent BALB/c mice, HDP-on cells, but not HDPs, are detected 1 day post-transplantation in the peritoneal cavity. Pretreatment of BALB/c mice with liposomal clodronate significantly enhances survival at day 7 for HDPs and HDP-on cells in the peritoneal cavity, spleen, and liver, but cells are undetectable at day 14. Short-term post-transplantation survival of HDPs is significantly improved using HDP-on and liposomal clodronate, opening a path for MΦ-based therapeutics.
ABSTRACT
1,2-Distigmasterylhemisuccinoyl-sn-glycero-3-phosphocholine (DSHemsPC) is a new lipid in which two molecules of stigmasterol (an inexpensive plant sterol) are covalently linked via a succinic acid to glycerophosphocholine. Our previous study revealed that liposome (Lip)-intercalated amphotericin B (AMB) prepared from DSHemsPC (DSHemsPC-AMB-Lip) possesses excellent colloidal properties and in vitro antifungal and antileishmanial activities similar to those of the liposomal AMB preparation AmBisome. The aim of this study was to determine the biodistribution and evaluate the antileishmanial effects of DSHemsPC-AMB-Lip in Leishmania major-infected BALB/c mice. The serum profile and tissue concentrations of AMB were similar in DSHemsPC-AMB-Lip- and AmBisome-treated mice after intravenous (i.v.) injection. Multiple i.v. doses of the micellar formulation of AMB (Fungizone; 1 mg/kg of body weight), DSHemsPC-AMB-Lip (5 mg/kg), and AmBisome (5 mg/kg) were used in L. major-infected BALB/c mouse models of early and established lesions. In a model of the early lesions of cutaneous leishmaniasis (CL), the results indicated that the level of footpad inflammation was significantly (P < 0.001) lower in mice treated with DSHemsPC-AMB-Lip and AmBisome than mice treated with empty liposomes or 5% dextrose. The splenic and footpad parasite load was also significantly (P < 0.001) lower in these groups of mice than in control mice that received 5% DW or free liposome. The in vivo activity of DSHemsPC-AMB-Lip was comparable to that of AmBisome, and both provided improved results compared to those achieved with Fungizone at the designated doses. The results suggest that systemic DSHemsPC-AMB-Lip administration may be useful for the treatment of leishmaniasis, and because it costs less to produce DSHemsPC-AMB-Lip than AmBisome, DSHemsPC-AMB-Lip merits further investigation.
Subject(s)
Amphotericin B/pharmacokinetics , Amphotericin B/therapeutic use , Antiprotozoal Agents/therapeutic use , Leishmania major/drug effects , Leishmaniasis, Cutaneous/drug therapy , Phosphatidylcholines/pharmacokinetics , Phosphatidylcholines/therapeutic use , Stigmasterol/analogs & derivatives , Animals , Antiprotozoal Agents/pharmacokinetics , Disease Models, Animal , Drug Administration Routes , Drug Carriers/therapeutic use , Female , Leishmania major/pathogenicity , Leishmaniasis, Cutaneous/parasitology , Liposomes/therapeutic use , Mice , Mice, Inbred BALB C , Parasite Load , Spleen/parasitology , Stigmasterol/pharmacokinetics , Stigmasterol/therapeutic useABSTRACT
We employed a recently introduced class of sterol-modified lipids (SML) to produce m-PEG-DSPE containing liposome compositions with a range of cis-platinum content release rates. SML have a cholesterol succinate attached to the phosphatidylglycerol head group and a fatty acid at the 2 position. These compositions were compared to the well-studied liposome phospholipid compositions: mPEG-DSPE/Hydrogenated Soy PC/cholesterol or mPEG-DSPE/POPC/cholesterol to determine the effect of the cis-platinum release extent on C26 tumor proliferation in the BALB/c colon carcinoma mouse model. The release rates of cis-platinum from liposomes composed of SML are a function of the acyl chain length. SML-liposomes with shorter acyl chain lengths C-8 provided more rapid cisplatin release, lower in vitro IC50, and were easier to formulate compared to liposomes using traditional phospholipid compositions. Similar to other liposome cis-platinum formulations, the half-life of m-PEG-DSPE SML liposome cisplatin is substantially longer than the free drug. This resulted in a higher tumor cisplatin concentration at 48h post-dosing compared to the free drug and higher Pt-DNA adducts in the tumor. Moreover, the maximum tolerated dose of the liposome formulations where up to four fold greater than the free drug. Using X-ray fluorescence spectroscopy on tumor sections, we compared the location of platinum, to the location of a fluorescence lipid incorporated in the liposomes. The liposome platinum co-localized with the fluorescent lipid and both were non-uniformly distributed in the tumor. Non-encapsulated Cis-platinum, albeit at a low concentration, was more uniformly distributed thorough the tumor. Three liposome formulations, including the well-studied hydrogenated HSPC composition, had better antitumor activity in the murine colon 26 carcinoma model as compared to the free drug at the same dose but the SML liposome platinum formulations did not perform better than the HSPC formulation.
Subject(s)
Antineoplastic Agents/administration & dosage , Cholesterol/chemistry , Cisplatin/administration & dosage , Phospholipids/chemistry , Animals , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Cell Line, Tumor , Cisplatin/chemistry , Cisplatin/pharmacology , Colonic Neoplasms/drug therapy , Delayed-Action Preparations , Female , Half-Life , Humans , Liposomes , Maximum Tolerated Dose , Mice, Inbred BALB C , Tissue DistributionABSTRACT
Doxil® is a complex parenteral doxorubicin (DOX) liposome formulation approved by the FDA. For generic doxorubicin liposomes, analyzing the release profile of DOX is important for quality control and comparability studies. However, there is no robust standard drug release assay available for doxorubicin liposomes. In this study, we describe a USP-4 apparatus assay capable of discriminating DOX liposomal formulations based on release profile. Establishment of the assay was hindered by limited DOX release from liposomes in physiological conditions at 37°C. The addition of NH4HCO3 to the release media facilitated DOX release proportionally to the salt concentration added but caused precipitation of released drug in USP-4 apparatus. Precipitation of DOX was avoided by adding hydroxypropyl-cyclodextrin (HP-CD) to the release medium. We optimized conditions for DOX release by varying a number of parameters such as: concentration of HP-CD, testing temperature, and concentration of tested samples. The optimized release medium contained: 100 mM NH4HCO3, 75 mM 2-(N-morpholino) ethanesulfonic acid (MES) and 5% w/v HP-CD, 5% w/v sucrose, 0.02% w/v NaN3 (pH 6). The drug release assay was performed at 45°C. The optimized release assay can discriminate between DOX liposomal formulations of different compositions, physicochemical properties, and prepared by different manufacturing methods. This indicates that the assay could be used to compare DOX release from generic DOX formulations to the innovator product Doxil®.
Subject(s)
Antibiotics, Antineoplastic/chemistry , Doxorubicin/analogs & derivatives , Technology, Pharmaceutical/instrumentation , Antibiotics, Antineoplastic/standards , Chemistry, Pharmaceutical , Chromatography, High Pressure Liquid , Doxorubicin/chemistry , Doxorubicin/standards , Drug Compounding , Drug Liberation , Liposomes , Particle Size , Polyethylene Glycols/chemistry , Polyethylene Glycols/standards , Solubility , Technology, Pharmaceutical/standardsABSTRACT
We utilized quantitative high-resolution single particle tracking to study the internalization and endosomal sorting of lipid nanoparticles (LNPs) by HeLa cells in vitro to gain a better understanding of how cells process LNPs that are used for siRNA delivery. We compared the trafficking of three formulations that have been demonstrated to deliver siRNA into cells. They were composed of either a tritratable anionic lipid, formulation of cholesterol hemisuccinate (CHEMS), or a titratatable cationic lipid formulation of 1,2-dilinoleyloxy-3-dimethylaminopropane (DLinDMA) or a non-titratable cationic formulation lipid formulation of 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP). They also contained either a substantial percentage of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) or cholesterol and 5 mole percent 1,2-dimyristoyl-sn-glycerol-[methoxy(polyethylene glycol)-2000 (PEG-DMG). We optically measured the endosomal pH experienced by individual LNPs, observed the internalization pathways used and tracked the particles as they co-localized with fluorescent protein tags on compartment-specific proteins, during endosomal sorting to the lysosome. The data revealed significant differences in the accumulation in subcellular compartments among the three formulations, which help to explain the observed effects LNP composition exerts on in vitro delivery efficiency.
Subject(s)
Lipids/chemistry , Nanoparticles/chemistry , Biological Transport/physiology , Cholesterol , Drug Delivery Systems , Fatty Acids, Monounsaturated , Fluorescent Dyes , HeLa Cells , Humans , Lipid Metabolism , Luciferases , Nanoparticles/metabolism , Phosphatidylethanolamines/chemistry , Polyethylene Glycols/chemistry , Propanolamines/chemistry , Quaternary Ammonium Compounds , RNA, Small Interfering , Triglycerides/chemistryABSTRACT
In the quest for better medicines, attention is increasingly turning to cell-based therapies. The rationale is that infused cells can provide a targeted therapy to precisely correct a complex disease phenotype. Between 1987 and 2010, autologous macrophages (MΦs) were used in clinical trials to treat a variety of human tumors; this approach provided a modest therapeutic benefit in some patients but no lasting remissions. These trials were initiated prior to an understanding of: the complexity of MΦ phenotypes, their ability to alter their phenotype in response to various cytokines and/or the environment, and the extent of survival of the re-infused MΦs. It is now known that while inflammatory MΦs can kill tumor cells, the tumor environment is able to reprogram MΦs into a tumorigenic phenotype; inducing blood vessel formation and contributing to a cancer cell growth-promoting milieu. We review how new information enables the development of large numbers of ex vivo generated MΦs, and how conditioning and gene engineering strategies are used to restrict the MΦ to an appropriate phenotype or to enable production of therapeutic proteins. We survey applications in which the MΦ is loaded with nanomedicines, such as liposomes ex vivo, so when the drug-loaded MΦs are infused into an animal, the drug is released at the disease site. Finally, we also review the current status of MΦ biodistribution and survival after transplantation into an animal. The combination of these recent advances opens the way for improved MΦ cell therapies.
Subject(s)
Cell Engineering , Cell Transplantation/methods , Macrophages/immunology , Macrophages/transplantation , Neoplasms/therapy , Animals , Cell Polarity/immunology , Clinical Trials as Topic , Disease Models, Animal , Humans , Macrophages/cytology , Neoplasms/immunologyABSTRACT
A variety of water-soluble polymers, when attached to a liposome, substantially increase liposome circulation half-life in animals. However, in certain conditions, liposomes modified with the most widely used polymer, polyethylene glycol (PEG), induce an IgM response resulting in an accelerated blood clearance (ABC) of the liposome upon the second injection. Modification of liposomes with other water-soluble polymers: HPMA (poly[N-(2-hydroxypropyl) methacrylamide]), PVP (poly(vinylpyrrolidone)), PMOX (poly(2-methyl-2-oxazoline)), PDMA (poly(N,N-dimethyl acrylamide)), and PAcM (poly(N-acryloyl morpholine)), increases circulation times of liposomes; but a precise comparison of their ability to promote long circulation or induce the ABC effect has not been reported. To obtain a more nuanced understanding of the role of polymer structure/MW to promote long circulation, we synthesized a library of polymer diacyl chain lipids with low polydispersity (1.04-1.09), similar polymer molecular weights (2.1-2.5kDa) and incorporated them into 100nm liposomes of a narrow polydispersity (0.25-1.3) composed of polymer-lipid/hydrogenated soy phosphatidylcholine/cholesterol/diD: 5.0/54.5/40/0.5. We confirm that HPMA, PVP, PMOX, PDMA and PAcM modified liposome have increased circulation times in rodents and that PVP, PDMA, and PAcM do not induce the ABC effect. We demonstrate for the first time, that HPMA does not cause an ABC effect whereas PMOX induces a pronounced ABC effect in rats. We find that a single dose of liposomes coated with PEG and PMOX generates an IgM response in rats towards the respective polymer. Finally, in this homologous polymer series, we observe a positive correlation (R=0.84 in rats, R=0.92 in mice) between the circulation time of polymer-modified liposomes and polymer viscosity; PEG and PMOX, the polymers that can initiate an ABC response were the two most viscous polymers. Our findings suggest that polymers that do not cause an ABC effect such as, HPMA or PVP, deserve further consideration as polymer coatings to improve the circulation of liposomes and other nanoparticles.
Subject(s)
Liposomes/blood , Liposomes/chemistry , Polymers/chemistry , Animals , Female , Immunoglobulin M/immunology , Liposomes/immunology , Male , Mice , Polyamines/blood , Polyamines/chemistry , Polyamines/immunology , Polyethylene Glycols/chemistry , Polyethylene Glycols/pharmacokinetics , Polymers/pharmacokinetics , Rats, WistarABSTRACT
Immunoglobulin G (IgG)-based drugs are arguably the most successful class of protein therapeutics due in part to their remarkably long blood circulation. This arises from IgG interaction with the neonatal Fc receptor, FcRn. FcRn is the central regulator of IgG and albumin homeostasis throughout life and is increasingly being recognized as an important player in autoimmune disease, mucosal immunity, and tumor immune surveillance. Various engineering approaches that hijack or disrupt the FcRn-mediated transport pathway have been devised to develop long-lasting and non-invasive protein therapeutics, protein subunit vaccines, and therapeutics for treatment of autoimmune and infectious disease. In this review, we highlight the diverse biological functions of FcRn, emerging therapeutic opportunities, as well as the associated challenges of targeting FcRn for drug delivery and disease therapy.
Subject(s)
Drug Delivery Systems , Histocompatibility Antigens Class I/metabolism , Immunoglobulin G/immunology , Receptors, Fc/metabolism , Animals , Autoimmune Diseases/drug therapy , Autoimmune Diseases/immunology , Biological Transport/drug effects , Communicable Diseases/drug therapy , Communicable Diseases/immunology , Histocompatibility Antigens Class I/immunology , Humans , Immunity, Mucosal , Receptors, Fc/immunologyABSTRACT
We explore a strategy to substantially increase the half-life of recombinant proteins by genetic fusion to FcIII, a 13-mer IgG-Fc domain binding peptide (IgGBP) originally identified by DeLano and co-workers at Genentech [DeLano WL, et al. (2000) Science 287:1279-1283]. IgGBP fusion increases the in vivo half-life of proteins by enabling the fusion protein to bind serum IgG, a concept originally introduced by DeLano and co-workers in a patent but that to the best of our knowledge has never been pursued in the scientific literature. To further investigate the in vitro and in vivo properties of IgGBP fusion proteins, we fused FcIII to the C-terminus of a model fluorescent protein, monomeric Katushka (mKate). mKate-IgGBP fusions are easily expressed in Escherichia coli and bind specifically to human IgG with an affinity of â¼ 40 nM and â¼ 20 nM at pH 7.4 and pH 6, respectively, but not to mouse or rat IgG isotypes. mKate-IgGBP binds the Fc-domain of hIgG1 at a site overlapping the human neonatal Fc receptor (hFcRn) and as a consequence inhibits the binding of hIgG1 to hFcRn in vitro. High affinity binding to human IgG also endows mKate-IgGBP with a long circulation half-life of â¼ 8 hr in mice, a 75-fold increase compared to unmodified mKate. Thus, IgGBP fusion significantly reduces protein clearance by piggybacking on serum IgG without substantially increasing protein molecular weight due to the small size of the IgGBP. These attractive features could result in protein therapies with reduced dose frequency and improved patient compliance.
Subject(s)
Cell Adhesion Molecules/metabolism , Fluorescent Dyes/metabolism , Immunoglobulin G/metabolism , Recombinant Fusion Proteins/pharmacokinetics , Animals , Cell Adhesion Molecules/genetics , Dogs , Escherichia coli/genetics , Escherichia coli/metabolism , Half-Life , Histocompatibility Antigens Class I/genetics , Histocompatibility Antigens Class I/metabolism , Humans , Hydrogen-Ion Concentration , Immunoglobulin G/chemistry , Madin Darby Canine Kidney Cells , Mice , Protein Binding , Rats , Receptors, Fc/genetics , Receptors, Fc/metabolism , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/metabolismABSTRACT
We describe a new class of charge inverted zwitterionic sulfated lipids (AS) with a cationic quaternary amine anchored at the membrane interface and an anionic sulfate moiety extended into the aqueous phase. These lipids have exceptionally high transition temperatures and assemble into lipid aggregates when dispersed in aqueous solutions.