Oligonucleotide Delivery across the Caco-2 Monolayer: The Design and Evaluation of Self-Emulsifying Drug Delivery Systems (SEDDS)

Oligonucleotides (OND) represent a promising therapeutic approach. However, their instability and low intestinal permeability hamper oral bioavailability. Well-established for oral delivery, self-emulsifying drug delivery systems (SEDDS) can overcome the weakness of other delivery systems such as long-term instability of nanoparticles or complicated formulation processes. Therefore, the present study aims to prepare SEDDS for delivery of a nonspecific fluorescently labeled OND across the intestinal Caco-2 monolayer. The hydrophobic ion pairing of an OND and a cationic lipid served as an effective hydrophobization method using either dimethyldioctadecylammonium bromide (DDAB) or 1,2-dioleoyl-3-trimethylammonium propane (DOTAP). This strategy allowed a successful loading of OND-cationic lipid complexes into both negatively charged and neutral SEDDS. Subjecting both complex-loaded SEDDS to a nuclease, the negatively charged SEDDS protected about 16% of the complexed OND in contrast to 58% protected by its neutral counterpart. Furthermore, both SEDDS containing permeation-enhancing excipients facilitated delivery of OND across the intestinal Caco-2 cell monolayer. The negatively charged SEDDS showed a more stable permeability profile over 120 min, with a permeability of about 2 × 10−7 cm/s, unlike neutral SEDDS, which displayed an increasing permeability reaching up to 7 × 10−7 cm/s. In conclusion, these novel SEDDS-based formulations provide a promising tool for OND protection and delivery across the Caco-2 cell monolayer.

A Novel LNP-based Chlamydia subunit vaccine formulation that induces Th1 responses without upregulating IL-17 provides equivalent protection in mice as formulations that induced IL-17 and Th1 cytokines

Sexually transmitted Chlamydia infections can lead to the development of debilitating diseases such as chronic pelvic pain, ectopic pregnancy, pelvic inflammatory disease, and infertility. It has been proposed that immunity against Chlamydia infection and disease may be determined by a balance of IL-17 signaling. We sought to evaluate novel formulations for a candidate Chlamydia vaccine, consisting of Chlamydia major outer membrane protein (MOMP) alone or in combination with polymorphic membrane protein D (PmpD) and polymorphic membrane protein G (PmpG) as target immunogens. Native MOMP (nMOMP) isolated from C. muridarum elementary bodies (EBs) and recombinant PmpD and PmpG proteins were adjuvanted with Monophosphoryl lipid A (MPLA), in one of two formulations containing either lipid nanoparticles (LNPs) or the cationic lipid dimethyldioctadecylammonium bromide (DDA). Antibody titers to C. muridarum, nMOMP, and EBs were evaluated by ELISA, and T-cell responses by intracellular cytokine staining (ICS). Protection from challenge was determined by qPCR and gross pathology. All mice immunized with the new vaccine formulations showed significantly higher antibody titers to nMOMP (P<0.001) and C. muridarum EBs (P<0.001), when compared to the negative control group (adjuvant alone). Antibody titers in vaccine groups with Monophosphoryl lipid A (MPLA)+LNP were higher as compared to the MPLA+DDA group (P<0.001) except for groups 6 (Cm nMOMP+PmpG+PmpD p73+PmpD p82+MPLA+DDA) vs 7 (Cm nMOMP+PmpG+PmpD p73+PmpD p82+MPLA+LNP) for both C. muridarum EBs and PmpG; the groups were not statistically significant. ICS analysis showed more robust CD4+ T-cell responses (IFN-γ/IL-2/TNF-α) in the dimethyldioctadecylammonium bromide (DDA) and LNP groups compared to the adjuvant alone group. The combination of DDA and MPLA gave robust Th17 responses in comparison to MPLA and LNP group. Immunized groups also showed protection from challenge with C. muridarum , as evidenced by a reduction in bacterial shedding from the vagina for all groups (P<0.003) compared to shedding from the adjuvant control, Group 1. Both vaccine formulations generated robust immunological responses and both vaccine formulations were protective by reducing bacterial shedding after challenge. This data indicates equal protection can be achieved without the induction of Th17 responses.

Systemic Administration of Proteoglycan Protects BALB/c Retired Breeder Mice from Experimental Arthritis

This study was undertaken to evaluate the prophylactic potential of proteoglycan (PG) administration in experimental arthritis. Female BALB/c retired breeder mice received two (2xPG50 and 2xPG100 groups) or three (3xPG50 group) intraperitoneal doses of bovine PG (50 μg or 100 μg) every three days. A week later the animals were submitted to arthritis induction by immunization with three i.p. doses of bovine PG associated with dimethyldioctadecylammonium bromide adjuvant at intervals of 21 days. Disease severity was daily assessed after the third dose by score evaluation. The 3xPG50 group showed significant reduction in prevalence and clinical scores. This protective effect was associated with lower production of IFN-γand IL-17 and increased production of IL-5 and IL-10 by spleen cells restimulatedin vitrowith PG. Even though previous PG administration restrained dendritic cells maturation this procedure did not alter the frequency of regulatory Foxp3+T cells. Lower TNF-αand IL-6 levels and higher expression of ROR-γand GATA-3 were detected in the paws of protected animals. A delayed-type hypersensitivity reaction confirmed specific tolerance induction. Taken together, these results indicate that previous PG inoculation determines a specific tolerogenic effect that is able to decrease severity of subsequently induced arthritis.

Biocompatible and thermo-responsive nanocapsule synthesis through vesicle templating

Thermo-responsive and biocompatible cross-linked nanocapsules were synthesized through dimethyldioctadecylammonium bromide (DODAB) vesicle templating. Due to their properties, they can be considered as promising nanocarriers in controlled drug delivery.

The effect of neutral helper lipids on the structure of cationic lipid monolayers

Successful drug delivery via lipid-based systems has often been aided by the incorporation of ‘helper lipids’. While these neutral lipids enhance the effectiveness of cationic lipid-based delivery formulations, many questions remain about the nature of their beneficial effects. The structure of monolayers of the cationic lipid dimethyldioctadecylammonium bromide (DODAB) alone, and mixed with a neutral helper lipid, either diolelyphosphatidylethanolamine or cholesterol at a 1 : 1 molar ratio was investigated at the air–water interface using a combination of surface pressure–area isotherms, Brewster angle microscopy (BAM) and specular neutron reflectivity in combination with contrast variation. BAM studies showed that while pure DODAB and DODAB with cholesterol monolayers showed fairly homogeneous surfaces, except in the regions of phase transition, monolayers of DODAB with diolelyphosphatidylethanolamine were, in contrast, inhomogeneous exhibiting irregular bean-shaped domains throughout. Neutron reflectivity data showed that while the thickness of the DODAB monolayer increased from 17 to 24 Å as it was compressed from a surface pressure of 5–40 mN m −1 , the thickness of the helper lipid-containing monolayers, over the same range of surface pressures, was relatively invariant at between 25 and 27 Å. In addition, the monolayers containing diolelyphosphatidylethanolamine were found to be more heavily hydrated than the monolayers of cationic lipid, alone or in combination with cholesterol, with hydration levels of 18 molecules of water per molecule of lipid being recorded for the diolelyphosphatidylethanolamine-containing monolayers at a surface pressure of 30 mN m −1 compared with only six and eight molecules of water per molecule of lipid for the pure DODAB monolayer and the cholesterol-containing DODAB monolayer, respectively.