trehalose-6-6--dibehenate and 1-2-distearoyllecithin

In this study, we have used a chemometrics-based method to correlate key liposomal adjuvant attributes with in-vivo immune responses based on multivariate analysis.. The liposomal adjuvant composed of the cationic lipid dimethyldioctadecylammonium bromide (DDA) and trehalose 6,6-dibehenate (TDB) was modified with 1,2-distearoyl-sn-glycero-3-phosphocholine at a range of mol% ratios, and the main liposomal characteristics (liposome size and zeta potential) was measured along with their immunological performance as an adjuvant for the novel, postexposure fusion tuberculosis vaccine, Ag85B-ESAT-6-Rv2660c (H56 vaccine). Partial least square regression analysis was applied to correlate and cluster liposomal adjuvants particle characteristics with in-vivo derived immunological performances (IgG, IgG1, IgG2b, spleen proliferation, IL-2, IL-5, IL-6, IL-10, IFN-γ).. While a range of factors varied in the formulations, decreasing the 1,2-distearoyl-sn-glycero-3-phosphocholine content (and subsequent zeta potential) together built the strongest variables in the model. Enhanced DDA and TDB content (and subsequent zeta potential) stimulated a response skewed towards a cell mediated immunity, with the model identifying correlations with IFN-γ, IL-2 and IL-6.. This study demonstrates the application of chemometrics-based correlations and clustering, which can inform liposomal adjuvant design.

Topics: Adjuvants, Immunologic; Animals; Bacterial Proteins; Cytokines; Female; Glycolipids; Immunity, Cellular; Immunoglobulins; Liposomes; Mice, Inbred C57BL; Multivariate Analysis; Mycobacterium tuberculosis; Phosphatidylcholines; Quaternary Ammonium Compounds; Vaccines

Cationic liposomes of dimethyldioctadecylammonium bromide (DDA) combined with trehalose 6,6'-dibehenate (TDB) elicit strong cell-mediated and antibody immune responses; DDA facilitates antigen adsorption and presentation while TDB potentiates the immune response. To further investigate the role of DDA, DDA was replaced with the neutral lipid of distearoyl-sn-glycero-3-phosphocholine (DSPC) over a series of concentrations and these systems investigated as adjuvants for the delivery of Ag85B-ESAT-6-Rv2660c, a multistage tuberculosis vaccine.. Liposomal were prepared at a 5 : 1 DDA-TDB weight ratio and DDA content incrementally replaced with DSPC. The physicochemical characteristics were assessed (vesicle size, zeta potential and antigen loading), and the ability of these systems to act as adjuvants was considered.. As DDA was replaced with DSPC within the liposomal formulation, the cationic nature of the vesicles decreases as does electrostatically binding of the anionic H56 antigen (Hybrid56; Ag85B-ESAT6-Rv2660c); however, only when DDA was completed replaced with DSPC did vesicle size increase significantly. T-helper 1 (Th1)-type cell-mediated immune responses reduced. This reduction in responses was attributed to the replacement of DDA with DSPC rather than the reduction in DDA dose concentration within the formulation.. These results suggest Th1 responses can be controlled by tailoring the DDA/DSPC ratio within the liposomal adjuvant system.

Topics: Adjuvants, Immunologic; Animals; Antigens; Cations; Female; Glycolipids; Immunity, Cellular; Liposomes; Mice; Mice, Inbred C57BL; Phosphatidylcholines; Quaternary Ammonium Compounds; Th1 Cells; Vaccines

One of the main reasons for the unmet medical need for mucosal vaccines is the lack of safe and efficacious mucosal adjuvants. The cationic liposome-based adjuvant system composed of dimethyldioctadecylammonium (DDA) bromide and trehalose 6,6'-dibehenate (TDB) is a versatile adjuvant that has shown potential for mucosal vaccination via the airways. The purpose of this study was to investigate the importance of the liposomal surface charge on the interaction with lung epithelial cells. Thus, the cationic DDA in the liposomes was subjected to a step-wise replacement with the zwitterionic distearoylphosphatidylcholine (DSPC). The liposomes were tested with the model protein antigen ovalbumin for the mucosal deposition, the effect on cellular viability and the epithelial integrity by using the two cell lines A549 and Calu-3, representing cells from the alveolar and the bronchiolar epithelium, respectively. The Calu-3 cells were cultured under different conditions, resulting in epithelia with a low and a high mucus secretion, respectively. A significantly larger amount of lipid and ovalbumin was deposited in the epithelial cell layer and in the mucus after incubation with the cationic liposomes, as compared to incubation with the neutral liposomes, which suggests that the cationic charge is important for the delivery. The integrity and the viability of the cells without a surface-lining mucus layer were decreased upon incubation with the cationic formulations, whereas the mucus appeared to retain the integrity and viability of the mucus-covered Calu-3 cells. Our in vitro results thus indicate that DDA/TDB liposomes might be efficiently and safely used as an adjuvant system for vaccines targeting the mucus-covered epithelium of the upper respiratory tract and the conducting airways.

Topics: Adjuvants, Immunologic; Adjuvants, Pharmaceutic; Cations; Cell Line, Tumor; Cell Survival; Epithelial Cells; Glycolipids; Humans; Lipids; Liposomes; Lung; Mucus; Ovalbumin; Phosphatidylcholines; Quaternary Ammonium Compounds; Respiratory Mucosa; Vaccines

The adjuvanticity of liposomes can be directed through formulation to develop a safe yet potent vaccine candidate. With the addition of the cationic lipid dimethyldioctadecylammonium bromide (DDA) to stable neutral distearoylphosphatidylcholine (DSPC):cholesterol (Chol) liposomes, vesicle size reduces while protein entrapment increases. The addition of the immunomodulator, trehalose 6,6-dibehenate (TDB) to either the neutral or cationic liposomes did not affect the physiochemical characteristics of these liposome vesicles. However, the protective immune response, as indicated by the amount of IFN-γ production, increases considerably when TDB is present. High levels of IFN-γ were observed for cationic liposomes; however, there was a marked reduction in IFN-γ release over time. Conversely, for neutral liposomes containing TDB, although the initial amount of IFN-γ was slightly lower than the cationic equivalent, the overall protective immune responses of these neutral liposomes were effectively maintained over time, generating good levels of protection. To that end, although the addition of DSPC and Chol reduced the protective immunity of DDA:TDB liposomes, relatively high protection was observed for the neutral counterpart, DSPC:Chol:TDB, which may offer an effective neutral alternative to the DDA:TDB cationic system, especially for the delivery of either zwitterionic (neutral) or cationic molecules or antigens.

Topics: Adjuvants, Immunologic; Animals; Female; Glycolipids; Humans; Interferon-gamma; Liposomes; Mice; Mice, Inbred C57BL; Phosphatidylcholines; Quaternary Ammonium Compounds; Recombinant Fusion Proteins; Tuberculosis; Tuberculosis Vaccines; Vaccines, Subunit