Enhanced immunostimulant activity and protective effect of a synthetic lipopeptide after liposomization against Plasmodium berghei infection in mice

Curcuminoids-loaded liposomes in combination with arteether protects against Plasmodium berghei infection in mice

Curcuminoids are poorly water-soluble compounds with promising antimalarial activity. To overcome some of the drawbacks of curcuminoids, we explored the potential of liposomes for the intravenous delivery of curcuminoids in a model of mouse malaria. The curcuminoids-loaded liposomes were formulated from phosphatidylcholine (soy PC) by the thin-film hydration method. Antimalarial activity of curcuminoids-loaded liposomes alone and in combination with α/β arteether when administered intravenously, was evaluated in Plasmodium berghei infected mice. Animals treated with curcuminoids-loaded liposomes showed lower parasitemia and higher survival when compared to control group (no treatment). Importantly, the combination therapy of curcuminoids-loaded liposomes (40 mg/kg body wt) along with α/β arteether (30 mg/kg body wt) was able to not only cure infected mice but also prevented recrudescence. These data suggest that curcuminoids-loaded liposomes may show promise as a formulation for anti-malarial therapy.

Curcuminoids-loaded lipid nanoparticles: novel approach towards malaria treatment

In the present work, curcuminoids-loaded lipid nanoparticles for parenteral administration were successfully prepared by a nanoemulsion technique employing high-speed homogenizer and ultrasonic probe. For the production of nanoparticles, trimyristin, tristerin and glyceryl monostearate were selected as solid lipids and medium chain triglyceride (MCT) as liquid lipid. Scanning electron microscopy (SEM) revealed the spherical nature of the particles with sizes ranging between 120 and 250 nm measured by photon correlation spectroscopy (PCS). The zeta potential of the particles ranged between -28 and -45 mV depending on the nature of the lipid matrix produced, which also influenced the entrapment efficiency (EE) and drug loading capacity (LC) found to be in the range of 80-94% and 1.62-3.27%, respectively. The LC increased reciprocally on increasing the amount of MCT as confirmed by differential scanning calorimetry (DSC). DSC analyses revealed that increasing imperfections within the lipid matrix allowed for increasing encapsulation parameters. Nanoparticles were further sterilized by filtration process which was found to be superior over autoclaving in preventing thermal degradation of thermo-sensitive curcuminoids. The in vivo pharmacodynamic activity revealed 2-fold increase in antimalarial activity of curcuminoids entrapped in lipid nanoparticles when compared to free curcuminoids at the tested dosage level.

Immunogenicity of Liposomes Containing Lipid Core Peptides and the Adjuvant Quil A

PURPOSE

The purpose of this study was to investigate the immunogenicity of liposomes containing mannosylated lipid core peptide (manLCP) constructs, both in vitro and in vivo, with or without the addition of the immune stimulating adjuvant Quil A.

METHODS

Mouse bone marrow dendritic cells (BMDC) were cultured with liposome formulations for 48 h, and the resulting level of BMDC activation was determined by flow cytometry. BMDC pulsed with liposome formulations were incubated with 5,6-carboxyfluoroscein diacetate succinimidyl ester-labeled T cells for 72 h and the resulting T cell proliferation was determined by flow cytometry. To investigate the immunogenicity of formulations in vivo, groups of C57Bl/6J mice were immunized by subcutaneous injection, and the resulting antigen-specific cytotoxic and protective immune responses toward tumor challenge evaluated.

RESULTS

Despite being unable to demonstrate the activation of BMDC, BMDC pulsed with liposomes containing manLCP constructs were able to stimulate the proliferation of naïve T cells in vitro. However, in vivo only liposomes containing both manLCP and Quil A were able to stimulate a strong antigen-specific cytotoxic immune response. Liposomes containing manLCP and Quil A within the same particle were able to protect against the growth of tumor cells to a similar level as if the antigen was administered in alum with CD4 help.

CONCLUSION

ManLCPs administered in liposomes are able to stimulate strong cytotoxic and protective immune responses if Quil A is also incorporated as an adjuvant.

Immunomodulatory activity of analog of muramyl dipeptide and their use as adjunct to chemotherapy of Leishmania donovani in hamster

In search of a potent immunomodulator to be used as an immunoprophylactic agent and as adjunct to chemotherapy against Leishmania infection, two analogs of muramyl dipeptide, viz. N.Ac-norMur-MeVal-D-isoGln (86/448) and N.AcMur-Acc-D-isoGln (89/729) were evaluated for desired activity. Effect of these peptides on cell mediated and humoral immunity was studied by immunizing the peptide treated mouse with sheep red blood cells (SRBC) and determining HA-titer, plaque forming cells assay and delayed type of hypersensitivity (DTH) response after 4-5 days. Both the peptides stimulated cell mediated immunity (CMI), humoral response as well as macrophage function in terms of super oxide anion (O2-) and nitric oxide (NO) generation. Mitogen induced lymphocyte proliferation and production of IL-2 and INF-gamma increased while that of IL-4 and IL-10 decreased by both the peptides showing a typical Th1 type response. After establishing the immunostimulatory activity, these peptides were evaluated for immunoprophylactic efficacy as well as for use as adjunct to chemotherapy with stibanate (SSG) against Leishmania donovani infection in golden hamster. These peptides were found quite effective in both the modes. In adjunct use the treatment may require lower dose of SSG and thereby reduce the chances of drug toxicity.