Browsing by Subject "Liposome"

Now showing 1 - 6 of 6

Open Access
Assessment of immune potency of SARS-CoV-2 VLP vaccine in mice, enhanced through different adjuvants and liposome complexation
(2023-08) Abraş, İrem Fatma
SARS-CoV-2, emerging in December 2019 in Wuhan, China, led to a swift global pandemic declaration in March 2020, prompting widespread vaccine development. Most vaccines target specific regions, mainly the spike protein. In our lab, we have employed an innovative virus-like particle (VLP) vaccine approach encompassing all four structural proteins of the virus: spike, nucleocapsid, membrane, and envelope. Our study utilizes sterically stabilized cationic liposomes (SSCL) to encapsulate VLPs expressing the Delta variant spike protein, along with various adjuvants: CpG ODN, poly(I:C), and 2’3’-cGAMP. We characterized liposomes using tunable resistive pulse sensing for size and concentration. In C57BL/6 mice, we administered primary and two booster injections on Day 0, Day 15, and Day 73, respectively, collecting blood samples at intervals (Day 14, Day 28, Day 42, Day 72, and Day 90). To assess vaccine impact on mouse humoral immunity, we conducted ELISAs for total IgG, IgG1, and IgG2c antibodies against recombinant Spike and the receptor-binding domain (RBD). IgG titers increased until Day 42, remained stable or slightly decreased on Day 72, and significantly rose on Day 90. We calculated IgG2c/IgG1 ratios, reflecting Th1 immune responses, revealing enhanced cellular immunity potential in groups with adjuvants compared to the VLP-only group. This study underscores the effectiveness of our VLP vaccine strategy in stimulating robust immune responses and opens avenues for further research and development.
Open Access
Cell penetrating peptide amphiphile integrated liposomal systems for enhanced delivery of cargo to tumor cells
(2013) Kılınç, Murat
Liposomes have been extensively utilized as effective nanocarriers due to their enhanced solubility, higher stability and greater ability to facilitate the slow release of encapsulated drugs compared to free drug administrations. Liposomes are also preferred as drug vectors due to their non-toxic nature, biodegradability and structural resemblance to the cell membrane. However, their low internalization efficiencies pose an important challenge for their use in drug delivery applications. Internalization issues inherent in many liposomal systems can be circumvented by the use of cell penetrating peptides, which non-covalently attach on the liposome surface and greatly enhance liposomal uptake in a receptor- and charge-dependent manner. In this study, we examined the liposomal dynamics effected through the integration of an amphiphilic cell penetrating peptide into a simple liposome system. Peptide amphiphiles with a cell penetrating arginine-rich domain were incorporated into liposomal membranes formed by negatively charged dioleoylphosphoglycerol (DOPG) phospholipids in the presence of cholesterol. Throughout the present study, we sought to analyze the effect of peptide incorporation on (a) the physical characteristics, such as size, surface potential and membrane polarity, of the liposomal membrane, (b) the alterations in the encapsulation and delivery mechanisms of hydrophilic (Rhodamine B) and hydrophobic (Nile Red) drug models and (c) the enhancement of therapeutic capability in liposomes loaded with the drugs Doxorubicin-HCl and Paclitaxel. Our results revealed that the modification of liposomes by cell penetrating peptide amphiphiles results in the improvement of cargo delivery and the enhancement of the therapeutic effects of the anticancer drugs Doxurubicin and Paclitaxel.
Open Access
FTIR studies of vitamin E-cholesterol-DPPC membrane interactions in CH2 region
(Springer-Verlag, 1996) Severcan, F.; Baykal, Ü.; Süzer, Ş.
Binary and ternary mixtures of α-tocopherol (αT), cholesterol and dipalmitoyl phosphatidylcholine (DPPC) in the form of multilamellar liposomes have been investigated by Fourier Transform Infrared Spectroscopy (FTIR). Investigation of frequencies, bandwidths and band shapes of CH2 stretching and scissoring bands indicate that the effect of αT is dominant in comparison with cholesterol and αT decreases the interaction of cholesterol with phospholipid membranes. © Springer-Verlag 1996.
Open Access
Inflammasome induction and immunostimulatory effects of CpG-ODN loaded liposomes containing DC-cholesterol
(Turkish Society of Immunology, 2013) Bayyurt, B.; Gürsel I.
Objectives: This study aims to investigate the effects of cholesterol content and cationic property of liposomes on immune response. Materials and methods: Liposomes containing high amounts of 3β-[N-(N',N'-dimethylaminoethane)-carbamoyl] cholesterol hydrochloride (DC-cholesterol) were prepared and loaded with K- and D-type CpG oligonucleotide (CpG-ODN) via dehydration-rehydration (DRV) method. After splenocytes and peritoneal exudate cells (PECs) primed with lipopolysaccharide (LPS) was incubated either with free or liposomal CpG-ODN counterparts, supernatants were collected and used in cytokine (IFN-g, IL-1γ and IL-1β) ELISA. Additionally, supernatants of PECs primed with LPS and stimulated with liposomes containing different doses of DC-cholesterol were collected and used in IL-1β ELISA assay. Results: Low-dose CpG-ODN loaded liposomal formulations induced higher immune activation than free CpG-ODN at the same dose. While high-dose liposomal CpG-ODN formulations decreased pro-inflammatory cytokine production in splenocytes, they increased the secretion of IL-1β. Inflammasome activation was increased in a dose dependent manner when PECs primed with LPS were incubated with only liposomes. Varying lipid molar ratios of DC-Cholesterol containing liposomes increased IL-1β production based on increasing lipid molar ratio. Conclusion: This study revealed that type and lipid ratio of liposomes may alter the cellular efficacy of the loaded immune-stimulatory agent and may initiate inflammasome activation. © 2014 Turkish Journal of Immunology.
Open Access
Investigation of improved immunostimulatory activity of D and K type CpG ODNs in liposomes
(2013) Dereli, İhsan
CpG ODNs are potent immunotherapeutic agents. In human, two major classes of CpG ODNs were shown to induce differential immune activation. D ODNs are strong IFNα inducers, thus promising antiviral agents, whereas K ODNs are effective against bacterial infections. However, their effects cannot be combined. When K and D type ODNs are used simultaneously, K ODN cancels D specific effect, a phenomenon known as K and D ODN dichotomy. The prime reason for this counter acting K ODN action was subcellular compartmentalization of K type CpG ODNs upon internalization. Besides, CpG ODNs have labile nature. When investigated in clinical trials, these nucleic acid based ligands are eliminated upon administration and displayed limited bio-availability due to nuclease digestion. Hence, efforts to protect in vivo performance, and increase stability and accumulation near target cells became a crucial task. Liposome technology offers a simple and mild approach to harbor these ODNs within membrane bilayers and protect them. We also reasoned that, if we use liposomes that alter subcellular fate of K and D ODNs, we can retain both K and D effect when liposomal ODNs are co-administered and the breadth of immunotherapeutic spectrum could be improved. This thesis was designed to understand and characterize different types of CpG ODNs loaded into different liposomes and aimed to determine their activities in different in vitro and in vivo settings. Our results revealed that when two different classes of clinically important CpG ODNs were encapsulated within proper liposome types, it is possible to recapitulate both K and D type ODN effect in PBMCs. Furthermore, in a vaccine model against H. felis, although initially did not induce significantly higher anti H.felis immunity, liposomal CpG ODNs improved persisting antibody levels for extended periods compared to free counterparts. Collectively, our results demonstrate that this platform allows more effective in vivo utilization of CpG ODNs and can be formulated to develop more efficient means to combat several health problems, ranging from cancer to allergy.
Open Access
Site-specific fluorescence polarization for studying the disaggregation of α-synuclein fibrils by small molecules
(American Chemical Society, 2017) Haney, C. M.; Cleveland, C. L.; Wissner, R. F.; Owei, L.; Robustelli, J.; Daniels, M. J.; Canyurt, M.; Rodriguez, P.; Ischiropoulos, H.; Baumgart, T.; Petersson, E. J.
Fibrillar aggregates of the protein α-synuclein (αS) are one of the hallmarks of Parkinson’s disease. Here, we show that measuring the fluorescence polarization (FP) of labels at several sites on αS allows one to monitor changes in the local dynamics of the protein after binding to micelles or vesicles, and during fibril formation. Most significantly, these site-specific FP measurements provide insight into structural remodeling of αS fibrils by small molecules and have the potential for use in moderate-throughput screens to identify small molecules that could be used to treat Parkinson’s disease. © 2016 American Chemical Society.