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Bhattacharya A, Falk ID, Moss FR, Weiss TM, Tran KN, Burns NZ, Boxer SG. Structure-function relationships in pure archaeal bipolar tetraether lipids. Chem Sci 2024:d4sc03788j. [PMID: 39149219 PMCID: PMC11320390 DOI: 10.1039/d4sc03788j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2024] [Accepted: 08/05/2024] [Indexed: 08/17/2024] Open
Abstract
Archaeal bipolar tetraether lipids (BTLs) are among the most unusual lipids occurring in nature because of their presumed ability to span the entire membrane to form a monolayer structure. It is believed that because of their unique structural organization and chemical stability, BTLs offer extraordinary adaptation to archaea to thrive in the most extreme milieus. BTLs have also received considerable attention for development of novel membrane-based materials. Despite their fundamental biological significance and biotechnological interests, prior studies on pure BTLs are limited because of the difficulty to extract them in pure form from natural sources or to synthesize them chemically. Here we have utilized chemical synthesis to enable in-depth biophysical investigations on a series of chemically pure glycerol dialkyl glycerol tetraether (GDGT) lipids. The lipids self-assemble to form membrane-bound vesicles encapsulating polar molecules in aqueous media, and reconstitute a functional integral membrane protein. Structural properties of the membranes were characterized via small-angle X-ray scattering (SAXS) and cryogenic electron microscopy (cryo-EM). SAXS studies on bulk aqueous dispersions of GDGT lipids over 10-90 °C revealed lamellar and non-lamellar phases and their transitions. Next we asked whether vesicles overwhelmingly composed of a single GDGT species can undergo fusion as it is difficult to conceptualize such behavior with the assumption that such membranes have a monolayer structure. Interestingly, we observed that GDGT vesicles undergo fusion with influenza virus with lipid mixing kinetics comparable to that with vesicles composed of monopolar phospholipids. Our results suggest that GDGT membranes may consist of regions with a bilayer structure or form bilayer structures transiently which facilitate fusion and thus offer insight into how archaea may perform important physiological functions that require dynamical membrane behavior.
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Affiliation(s)
- Ahanjit Bhattacharya
- Department of Chemistry, Stanford University Stanford CA 94305 USA
- Stanford Center for Innovation in Global Health, Stanford University Stanford CA 94305 USA
| | - Isaac D Falk
- Department of Chemistry, Stanford University Stanford CA 94305 USA
| | - Frank R Moss
- Linac Coherent Light Source, SLAC National Accelerator Laboratory Menlo Park CA 94025 USA
| | - Thomas M Weiss
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory Menlo Park CA 94025 USA
| | - Khoi N Tran
- Department of Chemistry, Stanford University Stanford CA 94305 USA
| | - Noah Z Burns
- Department of Chemistry, Stanford University Stanford CA 94305 USA
| | - Steven G Boxer
- Department of Chemistry, Stanford University Stanford CA 94305 USA
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2
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Sedlmayr VL, Schobesberger S, Spitz S, Ertl P, Wurm DJ, Quehenberger J, Spadiut O. Archaeal ether lipids improve internalization and transfection with mRNA lipid nanoparticles. Eur J Pharm Biopharm 2024; 197:114213. [PMID: 38346479 DOI: 10.1016/j.ejpb.2024.114213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 01/19/2024] [Accepted: 02/06/2024] [Indexed: 03/19/2024]
Abstract
Neutral and positively charged archaeal ether lipids (AEL) have been studied for their utilization as novel delivery systems for pDNA, showing efficient immune response with a strong memory effect while lacking noticeable toxicity. Recent technological advances placed mRNA lipid nanoparticles (LNPs) at the forefront of next-generation delivery systems; however, no study has examined AELs in mRNA delivery yet. In this study, we investigated either a crude lipid extract or the purified tetraether lipid caldarchaeol from Sulfolobus acidocaldarius as potential novel excipients for mRNA LNPs. Depending on their molar share in the respective LNP, particle uptake, and mRNA expression levels could be increased by up to 10-fold in in vitro transfection experiments using both primary cell sources (HSMM) and established cell lines (Caco-2, C2C12) compared to a well-known reference formulation. This increased efficiency might be linked to a substantial effect on endosomal escape, indicating fusogenic and lyotropic features of AELs. This study shows the high value of archaeal ether lipids for mRNA delivery and provides a solid foundation for future in vivo experiments and further research.
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Affiliation(s)
- Viktor Laurin Sedlmayr
- Research Division Integrated Bioprocess Development, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Gumpendorfer Straße 1a, Vienna 1060, Austria
| | - Silvia Schobesberger
- Research Division Organic & Biological Chemistry, Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163, Vienna 1060, Austria
| | - Sarah Spitz
- Research Division Organic & Biological Chemistry, Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163, Vienna 1060, Austria
| | - Peter Ertl
- Research Division Organic & Biological Chemistry, Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163, Vienna 1060, Austria
| | | | - Julian Quehenberger
- Research Division Integrated Bioprocess Development, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Gumpendorfer Straße 1a, Vienna 1060, Austria; NovoArc GmbH, Pottendorfer Straße 23-25, Vienna 1120, Austria
| | - Oliver Spadiut
- Research Division Integrated Bioprocess Development, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Gumpendorfer Straße 1a, Vienna 1060, Austria.
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3
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Fusion of Bipolar Tetraether Lipid Membranes Without Enhanced Leakage of Small Molecules. Sci Rep 2019; 9:19359. [PMID: 31852914 PMCID: PMC6920354 DOI: 10.1038/s41598-019-55494-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 11/21/2019] [Indexed: 01/19/2023] Open
Abstract
A major challenge in liposomal research is to minimize the leakage of encapsulated cargo from either uncontrolled passive permeability across the liposomal membrane or upon fusion with other membranes. We previously showed that liposomes made from pure Archaea-inspired bipolar tetraether lipids exhibit exceptionally low permeability of encapsulated small molecules due to their capability to form more tightly packed membranes compared to typical monopolar lipids. Here, we demonstrate that liposomes made of synthetic bipolar tetraether lipids can also undergo membrane fusion, which is commonly accompanied by content leakage of liposomes when using typical bilayer-forming lipids. Importantly, we demonstrate calcium-mediated fusion events between liposome made of glycerolmonoalkyl glycerol tetraether lipids with phosphatidic acid headgroups (GMGTPA) occur without liposome content release, which contrasts with liposomes made of bilayer-forming EggPA lipids that displayed ~80% of content release under the same fusogenic conditions. NMR spectroscopy studies of a deuterated analog of GMGTPA lipids reveal the presence of multiple rigid and dynamic conformations, which provide evidence for the possibility of these lipids to form intermediate states typically associated with membrane fusion events. The results support that biomimetic GMGT lipids possess several attractive properties (e.g., low permeability and non-leaky fusion capability) for further development in liposome-based technologies.
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Le Gall T, Barbeau J, Barrier S, Berchel M, Lemiègre L, Jeftić J, Meriadec C, Artzner F, Gill DR, Hyde SC, Férec C, Lehn P, Jaffrès PA, Benvegnu T, Montier T. Effects of a Novel Archaeal Tetraether-Based Colipid on the In Vivo Gene Transfer Activity of Two Cationic Amphiphiles. Mol Pharm 2014; 11:2973-88. [DOI: 10.1021/mp4006276] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tony Le Gall
- Unité
INSERM 1078, SFR ScInBioS; Université de Bretagne Occidentale, Université Européenne de Bretagne, 46 rue Félix Le Dantec, CS51819, 29218 Brest Cedex 02, France
- Plateforme
SynNanoVect, SFR ScInBioS; Université de Bretagne Occidentale, Université Européenne de Bretagne, Brest, France
| | - Julie Barbeau
- Ecole
Nationale Supérieure de Chimie de Rennes, Université Européenne de Bretagne, CNRS,
UMR 6226, 11 allée de Beaulieu,
CS 50837, 35708 Rennes Cedex 7, France
| | - Sylvain Barrier
- Ecole
Nationale Supérieure de Chimie de Rennes, Université Européenne de Bretagne, CNRS,
UMR 6226, 11 allée de Beaulieu,
CS 50837, 35708 Rennes Cedex 7, France
| | - Mathieu Berchel
- CEMCA,
CNRS UMR 6521, SFR ScInBioS, Université Européenne de Bretagne, Université de Brest, Brest, France
| | - Loïc Lemiègre
- Plateforme
SynNanoVect, SFR ScInBioS; Université de Bretagne Occidentale, Université Européenne de Bretagne, Brest, France
- Ecole
Nationale Supérieure de Chimie de Rennes, Université Européenne de Bretagne, CNRS,
UMR 6226, 11 allée de Beaulieu,
CS 50837, 35708 Rennes Cedex 7, France
| | - Jelena Jeftić
- Plateforme
SynNanoVect, SFR ScInBioS; Université de Bretagne Occidentale, Université Européenne de Bretagne, Brest, France
- Ecole
Nationale Supérieure de Chimie de Rennes, Université Européenne de Bretagne, CNRS,
UMR 6226, 11 allée de Beaulieu,
CS 50837, 35708 Rennes Cedex 7, France
| | - Cristelle Meriadec
- Institut
de Physique de Rennes, Université Européenne de Bretagne, Université de Rennes 1, UMR-CNRS 6251, Campus Beaulieu Bat.
11A, 35042 Rennes
Cedex, France
| | - Franck Artzner
- Institut
de Physique de Rennes, Université Européenne de Bretagne, Université de Rennes 1, UMR-CNRS 6251, Campus Beaulieu Bat.
11A, 35042 Rennes
Cedex, France
| | - Deborah R. Gill
- Gene Medicine
Group, Nuffield Division of Clinical Laboratory Sciences, University of Oxford,
John Radcliffe Hospital, Oxford, United Kingdom
| | - Stephen C. Hyde
- Gene Medicine
Group, Nuffield Division of Clinical Laboratory Sciences, University of Oxford,
John Radcliffe Hospital, Oxford, United Kingdom
| | - Claude Férec
- Unité
INSERM 1078, SFR ScInBioS; Université de Bretagne Occidentale, Université Européenne de Bretagne, 46 rue Félix Le Dantec, CS51819, 29218 Brest Cedex 02, France
| | - Pierre Lehn
- Unité
INSERM 1078, SFR ScInBioS; Université de Bretagne Occidentale, Université Européenne de Bretagne, 46 rue Félix Le Dantec, CS51819, 29218 Brest Cedex 02, France
| | - Paul-Alain Jaffrès
- Plateforme
SynNanoVect, SFR ScInBioS; Université de Bretagne Occidentale, Université Européenne de Bretagne, Brest, France
- CEMCA,
CNRS UMR 6521, SFR ScInBioS, Université Européenne de Bretagne, Université de Brest, Brest, France
| | - Thierry Benvegnu
- Plateforme
SynNanoVect, SFR ScInBioS; Université de Bretagne Occidentale, Université Européenne de Bretagne, Brest, France
- Ecole
Nationale Supérieure de Chimie de Rennes, Université Européenne de Bretagne, CNRS,
UMR 6226, 11 allée de Beaulieu,
CS 50837, 35708 Rennes Cedex 7, France
| | - Tristan Montier
- Unité
INSERM 1078, SFR ScInBioS; Université de Bretagne Occidentale, Université Européenne de Bretagne, 46 rue Félix Le Dantec, CS51819, 29218 Brest Cedex 02, France
- Plateforme
SynNanoVect, SFR ScInBioS; Université de Bretagne Occidentale, Université Européenne de Bretagne, Brest, France
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5
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Parmentier J, Thewes B, Gropp F, Fricker G. Oral peptide delivery by tetraether lipid liposomes. Int J Pharm 2011; 415:150-7. [DOI: 10.1016/j.ijpharm.2011.05.066] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 03/21/2011] [Accepted: 05/26/2011] [Indexed: 10/18/2022]
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6
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Chen ZX, Su XX, Deng SP. Molecular Recognition of Melamine by Vesicles Spontaneously Formed from Orotic Acid Derived Bolaamphiphiles. J Phys Chem B 2010; 115:1798-806. [DOI: 10.1021/jp106385x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Zhong-Xiu Chen
- Department of Applied Chemistry, College of Food & Biology Engineering, and ‡Food Sensory Lab, Zhejiang Gongshang University, Hangzhou, Zhejiang 310035, P. R. China
| | - Xiao-Xia Su
- Department of Applied Chemistry, College of Food & Biology Engineering, and ‡Food Sensory Lab, Zhejiang Gongshang University, Hangzhou, Zhejiang 310035, P. R. China
| | - Shao-Ping Deng
- Department of Applied Chemistry, College of Food & Biology Engineering, and ‡Food Sensory Lab, Zhejiang Gongshang University, Hangzhou, Zhejiang 310035, P. R. China
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Maiti K, Mitra D, Mitra RN, Panda AK, Das PK, Rakshit AK, Moulik SP. Self-Aggregation of Synthesized Novel Bolaforms and Their Mixtures with Sodium Dodecyl Sulfate (SDS) and Cetyltrimethylammonium Bromide (CTAB) in Aqueous Medium. J Phys Chem B 2010; 114:7499-508. [DOI: 10.1021/jp910527q] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kajari Maiti
- Centre for Surface Science, Department of Chemistry, Jadavpur University, Kolkata 700 032, India, Department of Biological Chemistry, Indian Association for Cultivation of Science, Kolkata 700 032, India, Department of Chemistry, University of North Bengal, Darjeeling 734 013, India, and Department of Natural Sciences, West Bengal University of Technology, Kolkata 700 064, India
| | - Debolina Mitra
- Centre for Surface Science, Department of Chemistry, Jadavpur University, Kolkata 700 032, India, Department of Biological Chemistry, Indian Association for Cultivation of Science, Kolkata 700 032, India, Department of Chemistry, University of North Bengal, Darjeeling 734 013, India, and Department of Natural Sciences, West Bengal University of Technology, Kolkata 700 064, India
| | - Rajendra N. Mitra
- Centre for Surface Science, Department of Chemistry, Jadavpur University, Kolkata 700 032, India, Department of Biological Chemistry, Indian Association for Cultivation of Science, Kolkata 700 032, India, Department of Chemistry, University of North Bengal, Darjeeling 734 013, India, and Department of Natural Sciences, West Bengal University of Technology, Kolkata 700 064, India
| | - Amiya K. Panda
- Centre for Surface Science, Department of Chemistry, Jadavpur University, Kolkata 700 032, India, Department of Biological Chemistry, Indian Association for Cultivation of Science, Kolkata 700 032, India, Department of Chemistry, University of North Bengal, Darjeeling 734 013, India, and Department of Natural Sciences, West Bengal University of Technology, Kolkata 700 064, India
| | - Prasanta K. Das
- Centre for Surface Science, Department of Chemistry, Jadavpur University, Kolkata 700 032, India, Department of Biological Chemistry, Indian Association for Cultivation of Science, Kolkata 700 032, India, Department of Chemistry, University of North Bengal, Darjeeling 734 013, India, and Department of Natural Sciences, West Bengal University of Technology, Kolkata 700 064, India
| | - Animesh K. Rakshit
- Centre for Surface Science, Department of Chemistry, Jadavpur University, Kolkata 700 032, India, Department of Biological Chemistry, Indian Association for Cultivation of Science, Kolkata 700 032, India, Department of Chemistry, University of North Bengal, Darjeeling 734 013, India, and Department of Natural Sciences, West Bengal University of Technology, Kolkata 700 064, India
| | - Satya P. Moulik
- Centre for Surface Science, Department of Chemistry, Jadavpur University, Kolkata 700 032, India, Department of Biological Chemistry, Indian Association for Cultivation of Science, Kolkata 700 032, India, Department of Chemistry, University of North Bengal, Darjeeling 734 013, India, and Department of Natural Sciences, West Bengal University of Technology, Kolkata 700 064, India
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Sprott GD, Côté JP, Jarrell HC. Glycosidase-induced fusion of isoprenoid gentiobiosyl lipid membranes at acidic pH. Glycobiology 2008; 19:267-76. [PMID: 19029107 DOI: 10.1093/glycob/cwn129] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A difficulty in explaining the mechanism whereby archaeal lipid membrane vesicles (archaeosomes) deliver entrapped protein antigens to the MHC class I cytosolic pathway from phagolysosomes of antigen-presenting cells has been the observation that they tend not to fuse. Here, we determine that archaeosomes, composed of archaeal isoprenoid mixtures of glyco and phospholipids, can be highly fusogenic when exposed to the pH and enzymes found in late phagolysosomes. Fusions were strictly dependent on acidic pH and the presence of alpha- or beta-glucosidase. Resonance energy transfer (RET) assays demonstrated that fusion conditions induced lipid mixing of archaeosome lipids with self-unlabeled archaeosomes. Because PC/PG/cholesterol liposomes by themselves did not fuse, it was possible to unequivocally show a fusion of rhodamine-labeled liposomes with archaeosomes by fluorescence microscopy and to demonstrate lipid mixing between labeled liposomes and archaeosomes by the RET assay. Radiotracer and (1)H NMR studies revealed that glycolipids in fused archaeosomes were not degraded significantly by glucosidase treatment during fusion. Rather, the glucosidases dramatically induced small archaeosomes to rapidly and visually aggregate at pH 4.8, but not 6.8, thus bringing membranes together appropriately as a first step in the fusion process. (1)H NMR was used to demonstrate that conditions causing aggregation correlated with binding of glucosidase to the archaeosomes. Binding at acidic pH occurred by the electrostatic interaction of positively charged glucosidase with the anionic phospholipids, although the interaction also occurred with the gentiobiosyl lipids. The data indicate a mechanism of membrane-membrane fusion for archaeal glycolipid membranes induced by glycosidase and illustrate the importance for inclusion of glycolipids in compositions of vesicles designed to deliver protein antigens to the cytosol for MHC class I presentation.
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Affiliation(s)
- G Dennis Sprott
- Institute for Biological Sciences, National Research Council, 100 Sussex Drive, Ottawa, ON K1A OR6, Canada.
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10
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Bailey A, Zhukovsky M, Gliozzi A, Chernomordik LV. Liposome composition effects on lipid mixing between cells expressing influenza virus hemagglutinin and bound liposomes. Arch Biochem Biophys 2005; 439:211-21. [PMID: 15963452 DOI: 10.1016/j.abb.2005.05.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2005] [Revised: 05/03/2005] [Accepted: 05/05/2005] [Indexed: 11/23/2022]
Abstract
The involvement of contacting and distal lipid monolayers in different stages of protein-mediated fusion was studied for fusion mediated by influenza virus hemagglutinin. Inclusion of non-bilayer lipids in the composition of the liposomes bound to hemagglutinin-expressing cells affects fusion triggered by low pH. Lysophosphatidylcholine added to the outer membrane monolayers inhibits fusion. The same lipid added to the inner monolayer of the liposomes promotes both lipid and content mixing. In contrast to the inverted cone-shaped lysophosphatidylcholine, lipids of the opposite effective shape, oleic acid or cardiolipin with calcium, present in the inner monolayers inhibit fusion. These results along with fusion inhibition by a bipolar lipid that does not support peeling of one monolayer of the liposomal membrane from the other substantiate the hypothesis that fusion proceeds through a local hemifusion intermediate. The transition from hemifusion to the opening of an expanding fusion pore allows content mixing and greatly facilitates lipid mixing between liposomes and cells.
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Affiliation(s)
- Austin Bailey
- Section on Membrane Biology, Laboratory of Cellular and Molecular Biophysics, NICHD, NIH, Bethesda, MD, USA
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11
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Gurnani K, Kennedy J, Sad S, Sprott GD, Krishnan L. Phosphatidylserine Receptor-Mediated Recognition of Archaeosome Adjuvant Promotes Endocytosis and MHC Class I Cross-Presentation of the Entrapped Antigen by Phagosome-to-Cytosol Transport and Classical Processing. THE JOURNAL OF IMMUNOLOGY 2004; 173:566-78. [PMID: 15210818 DOI: 10.4049/jimmunol.173.1.566] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Archaeal isopranoid glycerolipid vesicles (archaeosomes) serve as strong adjuvants for cell-mediated responses to entrapped Ag. We analyzed the processing pathway of OVA entrapped in archaeosomes composed of Methanobrevibacter smithii lipids, high in archaetidylserine (OVA-archaeosomes). In vitro, OVA-archaeosomes stimulated spleen cells from OVA-TCR-transgenic mice, D011.10 (CD4(+) cells expressing OVA(323-339) TCR) or OT1 (>90% CD8(+) OVA(257-264) cells), indicating both MHC class I and II presentations. In vivo, when naive (Thy1.2(+)) CFSE-labeled OT1 cells were transferred into OVA-archaeosome-immunized Thy 1.1(+) recipient mice, there was profound accumulation and cycling of donor-specific cells, and differentiation of H-2K(b)Ova(257-264) CD8(+) T cells into CD44(high)CD62L(low) effectors. Both macrophages and dendritic cells (DCs) efficiently cross-presented OVA-archaeosomes on MHC class I. Blocking phagocytosis by phosphatidylserine-specific receptor agonists strongly inhibited MHC class I presentation of OVA-archaeosomes, whereas blocking mannose receptors or FcRs lacked effect, indicating specific recognition of the archaetidylserine head group of M. smithii lipids by APCs. In addition, inhibitors of endosomal acidification blocked MHC class I processing of OVA-archaeosomes, whereas endosomal protease inhibitors lacked effect, suggesting acidification-dependent phagosome-to-cytosol diversion. Proteasomal inhibitors blocked OVA-archaeosome MHC class I presentation, confirming cytosolic processing. Both in vitro and in vivo, OVA-archaeosome MHC class I presentation required TAP. Ag-free archaeosomes also activated DC costimulation and cytokine production, without overt inflammation. Phosphatidylserine-specific receptor-mediated endocytosis is a mechanism of apoptotic cell clearance and DCs cross-present Ags sampled from apoptotic cells. Our results reveal the novel ability of archaeosomes to exploit this mechanism for cytosolic MHC class I Ag processing, and provide an effective particulate vaccination strategy.
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Affiliation(s)
- Komal Gurnani
- Institute for Biological Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, Canada K1A 0R6
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12
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Structure and permeability properties of biomimetic membranes of bolaform archaeal tetraether lipids. J Memb Sci 2002. [DOI: 10.1016/s0376-7388(01)00771-2] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Patel GB, Sprott GD. Archaeobacterial ether lipid liposomes (archaeosomes) as novel vaccine and drug delivery systems. Crit Rev Biotechnol 2000; 19:317-57. [PMID: 10723627 DOI: 10.1080/0738-859991229170] [Citation(s) in RCA: 147] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Liposomes are artificial, spherical, closed vesicles consisting of one or more lipid bilayer(s). Liposomes made from ester phospholipids have been studied extensively over the last 3 decades as artificial membrane models. Considerable interest has been generated for applications of liposomes in medicine, including their use as diagnostic reagents, as carrier vehicles in vaccine formulations, or as delivery systems for drugs, genes, or cancer imaging agents. The objective of this article is to review the properties and potential applications of novel liposomes made from the membrane lipids of Archaeobacteria (Archaea). These lipids are unique and distinct from those encountered in Eukarya and Bacteria. Polar glycerolipids make up the bulk of the membrane lipids, with the remaining neutral lipids being primarily squalenes and other hydrocarbons. The polar lipids consist of regularly branched, and usually fully saturated, phytanyl chains of 20, 25, or 40 carbon length, with the 20 and 40 being most common. The phytanyl chains are attached via ether bonds to the sn-2,3 carbons of the glycerol backbone(s). It has been shown only recently that total polar lipids of archaeobacteria, and purified lipid fractions therefrom, can form liposomes. We refer to liposomes made with any lipid composition that includes ether lipids characteristic of Archaeobacteria as archaeosomes to distinguish them from vesicles made from the conventional lipids obtained from eukaryotic or eubacterial sources or their synthetic analogs. In general, archaeosomes demonstrate relatively higher stabilities to oxidative stress, high temperature, alkaline pH, action of phospholipases, bile salts, and serum proteins. Some archaeosome formulations can be sterilized by autoclaving, without problems such as fusion or aggregation of the vesicles. The uptake of archaeosomes by phagocytic cells can be up to 50-fold greater than that of conventional liposome formulations. Studies in mice have indicated that systemic administration of several test antigens entrapped within certain archaeosome compositions give humoral immune responses that are comparable to those obtained with the potent but toxic Freund's adjuvant. Archaeosome compositions can be selected to give a prolonged, sustained immune response, and the generation of a memory response. Tissue distribution studies of archaeosomes administered via various systemic and peroral routes indicate potential for targeting to specific organs. All in vitro and in vivo studies performed to date indicate that archaeosomes are safe and do not invoke any noticeable toxicity in mice. The stability, tissue distribution profiles, and adjuvant activity of archaeosome formulations indicate that they may offer a superior alternative to the use of conventional liposomes, at least for some biotechnology applications.
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Affiliation(s)
- G B Patel
- Institute for Biological Sciences, National Research Council of Canada, Ottawa, Ontario, Canada.
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14
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Abstract
Membrane fusion is essential for cell survival and has attracted a great deal of both theoretical and experimental interest. Fluorescence (de)quenching measurements were designed to distinguish between bilayermerging and vesicle-mixing. Theoretical studies and various microscopic and diffraction methods have elucidated the mechanism of membrane fusion. These have revealed that membrane proximity and high defect density in the adjacent bilayers are the only prerequisites for fusion. Intermediates, such as stalk or inverse micellar structures can, but need not, be involved in vesicle fusion. Nonlamellar phase creation is accompanied by massive membrane fusion although it is not a requirement for bilayer merging. Propensity for membrane fusion is increased by increasing the local membrane disorder as well by performing manipulations that bring bilayers closer together. Membrane rigidification and enlarged bilayer separation opposes this trend. Membrane fusion is promoted by defects created in the bilayer due to the vicinity of lipid phase transition, lateral phase separation or domain generation, high local membrane curvature, osmotic or electric stress in or on the membrane; the addition of amphiphats or macromolecules which insert themselves into the membrane, freezing or other mechanical membrane perturbation have similar effects. Lowering the water activity by the addition of water soluble polymers or by partial system dehydration invokes membrane aggregation and hence facilitates fusion; as does the membrane charge neutralization after proton or other ion binding to the lipids and intermembrane scaffolding by proteins or other macromolecules. The alignment of defect rich domains and polypeptides or protein binding is pluripotent: not only does it increase the number of proximal defects in the bilayers, it triggers the vesicle aggregation and is fusogenic. Exceptions are the bound molecules that create steric or electrical barriers between the membranes which prevent fusion. Membrane fusion can be non-leaky but it is very common to lose material from the vesicle interior during the later stages of membrane unification, that is, after a few hundred microseconds following the induction of fusion.
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Affiliation(s)
- G Cevc
- Medizinische Biophysik, Technische Universität München, Klinikum r.d.I., Ismaningerstrasse 22, D-81675, Munich, Germany
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