Inhaled lipid nanocarriers for pulmonary delivery of glucocorticoids: Previous strategies, recent advances and key factors description.

In view of the strong anti-inflammatory activity of glucocorticoids (GC) they are used in the treatment of almost all inflammatory lung diseases. In particular, inhaled GC (IGC) allow high drug concentrations to be deposited in the lung and may reduce the incidence of adverse effects associated with systemic administration. However, rapid absorption through the highly absorbent surface of the lung epithelium may limit the success of localized therapy. Therefore, inhalation of GC incorporated into nanocarriers is a possible approach to overcome this drawback. In particular, lipid nanocarriers, which showed high pulmonary biocompatibility and are well known in the pharmaceutical industry, have the best prospects for pulmonary delivery of GC by inhalation. This review provides an overview of the pre-clinical applications of inhaled GC-lipid nanocarriers based on several key factors that will determine the efficiency of local pulmonary GC delivery: 1) stability to nebulization, 2) deposition profile in the lungs, 3) mucociliary clearance, 4) selective accumulation in target cells, 5) residence time in the lung and systemic absorption and 6) biocompatibility. Finally, novel preclinical pulmonary models for inflammatory lung diseases are also discussed.

Bacterioruberin from Haloarchaea plus dexamethasone in ultra-small macrophage-targeted nanoparticles as potential intestinal repairing agent.

Oral administration of antioxidant and anti-inflammatory drugs have the potential to improve the current therapy of inflammatory bowel disease. Success of oral treatments, however, depends on the capacity of drugs to remain structurally stable along the gastrointestinal tract, and on the feasibility of accessing the target cells. Delivering anti-inflammatory and antioxidant drugs to macrophages using targeted nanoparticles, could make treatments more efficient. In this work structural features and in vitro activity of macrophage-targeted nanostructured archaeolipid carriers (NAC) containing the high antioxidant dipolar C50 carotenoid bacterioruberin (BR) plus dexamethasone (Dex): NAC-Dex, are described. Ultra-small (66 nm), -32 mV ζ potential, 1200 µg Dex /ml NAC-Dex, consisted of a compritol and BR core, covered by a shell of sn 2,3 ether linked archaeolipids and Tween 80 (2: 2: 1.2: 3 % w/w) were obtained. NAC-Dex were extensively captured by macrophages and Caco-2 cells and displayed high anti-inflammatory and antioxidant activities on a gut inflammation model made of Caco-2 cells and lipopolysaccharide stimulated THP-1 derived macrophages reducing 65 % and 55 % TNF-α and IL-8 release, respectively and 60 % reactive oxygen species production. NAC-Dex also reversed the morphological changes induced by inflammation and increased the transepithelial electrical resistance, partly reconstituting the barrier function. Activity of BR and Dex in NAC-Dex was partially protected after simulated gastrointestinal digestion, improving the chances of BR-Dex joint activity. Results suggest that oral NAC-Dex deserve further exploration as intestinal barrier repairing agent.

Ultra-small solid archaeolipid nanoparticles for active targeting to macrophages of the inflamed mucosa.

AIM: Develop nanoparticulate agents for oral targeted delivery of dexamethasone (Dex) to macrophages of inflamed mucosa. MATERIALS & METHODS: Solid archaeolipid nanoparticles (SAN-Dex) (compritol/Halorubrum tebenquichense polar archaeolipids/soybean phosphatidylcholine/Tween-80 4; 0.9; 0.3; 3% w/w) loaded with Dex were prepared. Their mucopenetration, stability under digestion and in vitro anti-inflammatory activity, were determined. RESULTS: Ultra-small SAN-Dex strongly reduced the levels of TNF-α, IL-6 and IL-12 on J774A1 cells stimulated with lipopolysaccharides as compared with free Dex or loaded in ordinary solid lipid nanoparticles-Dex. After in vitro digestion, the anti-inflammatory activity of SAN-Dex was retained, while that of solid lipid nanoparticles-Dex was lost. CONCLUSION: Because of their structural and pharmacodynamic features, SAN-Dex may be suitable for oral targeted delivery to inflamed mucosa.

Ultradeformable Archaeosomes for Needle Free Nanovaccination with Leishmania braziliensis Antigens.

Total antigens from Leishmania braziliensis promastigotes, solubilized with sodium cholate (dsLp), were formulated within ultradeformable nanovesicles (dsLp-ultradeformable archaeosomes, (dsLp-UDA), and dsLp-ultradeformable liposomes (dsLp-UDL)) and topically administered to Balb/c mice. Ultradeformable nanovesicles can penetrate the intact stratum corneum up to the viable epidermis, with no aid of classical permeation enhancers that can damage the barrier function of the skin. Briefly, 100 nm unilamellar dsLp-UDA (soybean phosphatidylcholine: Halorubrum tebenquichense total polar lipids (TPL): sodium cholate, 3:3:1 w:w) of -31.45 mV Z potential, containing 4.84 ± 0.53% w/w protein/lipid dsLp, 235 KPa Young modulus were prepared. In vitro, dsLp-UDA was extensively taken up by J774A1 and bone marrow derive cells, and the only that induced an immediate secretion of IL-6, IL-12p40 and TNF-α, followed by IL-1ß, by J774A1 cells. Such extensive uptake is a key feature of UDA ascribed to the highly negatively charged archaeolipids of the TPL, which are recognized by a receptor specialized in uptake and not involved in downstream signaling. Despite dsLp alone was also immunostimulatory on J774A1 cells, applied twice a week on consecutive days along 7 weeks on Balb/c mice, it raised no measurable response unless associated to UDL or UDA. The highest systemic response, IgGa2 mediated, 1 log lower than im dsLp Al2O3, was elicited by dsLp-UDA. Such findings suggest that in vivo, UDL and UDA acted as penetration enhancers for dsLp, but only dsLp-UDA, owed to its pronounced uptake by APC, succeeded as topical adjuvants. The actual TPL composition, fully made of sn2,3 ether linked saturated archaeolipids, gives the UDA bilayer resistance against chemical, physical and enzymatic attacks that destroy ordinary phospholipids bilayers. Together, these properties make UDA a promising platform for topical drug targeted delivery and vaccination, that may be of help for countries with a deficient healthcare system.

Enhanced photodynamic leishmanicidal activity of hydrophobic zinc phthalocyanine within archaeolipids containing liposomes.

In this work, the in vitro anti-Leishmania activity of photodynamic liposomes made of soybean phosphatidylcholine, sodium cholate, total polar archaeolipids (TPAs) extracted from the hyperhalophile archaea Halorubrum tebenquichense and the photosensitizer zinc phthalocyanine (ZnPcAL) was compared to that of ultradeformable photodynamic liposomes lacking TPAs (ZnPcUDLs). We found that while ZnPcUDLs and ZnPcALs (130 nm mean diameter and -35 mV zeta potential) were innocuous against promastigotes, a low concentration (0.01 µM ZnPc and 7.6 µM phospholipids) of ZnPcALs irradiated at a very low-energy density (0.2 J/cm(2)) eliminated L. braziliensis amastigotes from J774 macrophages, without reducing the viability of the host cells. In such conditions, ZnPcALs were harmless for J774 macrophages, HaCaT keratinocytes, and bone marrow-derived dendritic cells. Therefore, topical photodynamic treatment would not likely affect skin-associated lymphoid tissue. ZnPcALs were extensively captured by macrophages, but ZnPcUDLs were not, leading to 2.5-fold increased intracellular delivery of ZnPc than with ZnPcUDLs. Despite mediating low levels of reactive oxygen species, the higher delivery of ZnPc and the multiple (caveolin- and clathrin-dependent plus phagocytic) intracellular pathway followed by ZnPc would have been the reason for the higher antiamastigote activity of ZnPcALs. The leishmanicidal activity of photodynamic liposomal ZnPc was improved by TPA-containing liposomes.

Structural features of ultradeformable archaeosomes for topical delivery of ovalbumin.

The ultradeformable archaeosomes (UDA, made of total polar archaeolipids (TPA) extracted from the extreme halophile archaea Halorubrum tebenquichense:soybean phosphatidylcholine (SPC):sodium cholate (NaChol), 3:3:1 w:w), are promising topical adjuvants showing high deformability, an essential property for intact skin penetration up to the viable epidermis/dermis. To gain insights on UDA structure, the interactions between TPA, SPC and the edge activator NaChol, were assessed by electrospray ionization mass spectroscopy (ESI-MS) and confocal fluorescence microscopy of giant unilamellar vesicles (GUV). The non covalent heterodimers NaChol-SPC, NaChol-phosphatidylglycerophosphate methyl ether (PGPMe), NaChol-sulfated diglycosyl diphytanyl-glycerol diether (SDGD5) and SPC-PGPMe detected in the gas phase by ESI-MS after direct infusion of UDA, together with the homogeneous partition of FASTDiO and DiIC18 in GUV suggested that in these proportions, lipids and NaChol were miscible. We propose therefore, a model where in UDA the SPC diluted sufficient enough in the rich PGPMe TPA, so as to the low lateral mobility of molecules (typical of rich in PGPMe bilayers) was no longer experienced. We also found that 50µm deep within in vitro human skin canyons, the fluorescence of Alexa fluor 647-ovalbumin in UDL was ∼1.5 folds higher than in UDA, indicating a potential steric hindrance of the voluminous structure of PGPMe UDA bilayer, to the penetration of a particulate cargo such as the 7nm diameter ovalbumin. According to these observations, a further reduction in PGPMe - a lipid playing no immune role - content could help to improve the performance of UDA as topical adjuvants.

Archaeosomes display immunoadjuvant potential for a vaccine against Chagas disease.

Archaeosomes (ARC), vesicles made from lipids extracted from Archaea, display strong adjuvant properties. In this study, we evaluated the ability of the highly stable ARC formulated from total polar lipids of a new Halorubrum tebenquichense strain found in Argentinean Patagonia, to act as adjuvant for soluble parasite antigens in developing prophylactic vaccine against the intracellular protozoan T. cruzi, the etiologic agent of Chagas disease. We demonstrated for the first time that C3H/HeN mice subcutaneously immunized with trypanosomal antigens entrapped in these ARC (ARC-TcAg) rapidly developed higher levels of circulating T. cruzi antibodies than those measured in the sera from animals receiving the antigen alone. Enhanced humoral responses elicited by ARC-TcAg presented a dominant IgG2a antibody isotype, usually associated with Th1-type immunity and resistance against T. cruzi. More importantly, ARC-TcAg-vaccinated mice displayed reduced parasitemia during early infection and were protected against an otherwise lethal challenge with the virulent Tulahuén strain of the parasite. Our findings suggest that, as an adjuvant, H. tebenquichense-derived ARC may hold great potential to develop a safe and helpful vaccine against this relevant human pathogen.

Ultradeformable archaeosomes as new topical adjuvants.

Ultradeformable archaeosomes (UDA) are vesicles made of soybean phosphatidylcholine (SPC), sodium cholate (NaChol) and polar lipids from Halorubrum tebenquichense (3:1:3 wt/wt). Although ultradeformable liposomes (UDL, made of SPC and NaChol at 6:1 wt/wt) and UDA were neither captured nor caused cytotoxicity on keratinocytes, UDA was avidly captured by macrophages, their viability being reduced by 0.4-1.6 mg/mL phospholipids by 25 to 60%. Instead, UDL were poorly captured and caused no toxicity. Balb/C mice immunized by the topical route with four doses of ovalbumin (OVA)-loaded UDA, at 75 µg OVA/600 µg phospholipids (125 nm mean size and -42 mV zeta potential), induced IgG titers tenfold to 100-fold higher than those immunized with OVA-loaded UDL at the same dosage. Both matrices penetrate to the same skin depth (nearly 10 µm after 1 hour on excised human skin), being the higher topical adjuvancy and higher phagocytic uptake of UDA related to its glycolipid content. FROM THE CLINICAL EDITOR: This work summarizes key findings related to the development of ultradeformable archaeosomes as vehicles utilized in transdermal delivery systems with improved skin penetration.

M cells prefer archaeosomes: an in vitro/in vivo snapshot upon oral gavage in rats.

The archaeolipids (lipids extracted from archaebacterias) are non saponificable molecules that form self sealed mono or bilayers (archaeosomes-ARC). Different to liposomes with bilayers made of conventional glycerophospholipids, the bilayer of ARC posses a higher structural resistance to physico chemical and enzymatic degradation and surface hydrophobicity. In this work we have compared the binding capacity of ARC exclusively made of archaeols containing a minor fraction of sulphoglycophospholipids, with that of liposomes in gel phase on M-like cells in vitro. The biodistribution of the radiopharmaceutical (99m)Tc-DTPA loaded in ARC vs that of liposomes upon oral administration to Wistar rats was also determined. The fluorescence of M-like cells upon 1 and 2h incubation with ARC loaded with the hydrophobic dye Rhodamine-PE (Rh-PE) and the hydrophilic dye pyranine (HPTS) dissolved in the aqueous space, was 4 folds higher than upon incubation with equally labeled liposomes. Besides, 15% of Rh-PE and 13 % of HPTS from ARC and not from liposomes, were found in the bottom wells, a place that is equivalent to the basolateral pocket from M cells. This fact suggested the occurrence of transcytosis of ARC. Finally, 4 h upon oral administration, ARC were responsible for the 22.3 % (3.5 folds higher than liposomes) shuttling of (99m)Tc-DTPA to the blood circulation. This important amount of radioactive marker in blood could be a consequence of an extensive uptake of ARC by M cells in vivo, probably favored by their surface hydrophobicity. Taken together, these results suggested that ARC, proven their adjuvant capacity when administered by parenteral route and high biocompatibility, could be a suitable new type of nanoparticulate material that could be used as adjuvants by the oral route.

Archaeosomes made of Halorubrum tebenquichense total polar lipids: a new source of adjuvancy.

BACKGROUND: Archaeosomes (ARC), vesicles prepared from total polar lipids (TPL) extracted from selected genera and species from the Archaea domain, elicit both antibody and cell-mediated immunity to the entrapped antigen, as well as efficient cross priming of exogenous antigens, evoking a profound memory response. Screening for unexplored Archaea genus as new sources of adjuvancy, here we report the presence of two new Halorubrum tebenquichense strains isolated from grey crystals (GC) and black mood (BM) strata from a littoral Argentinean Patagonia salt flat. Cytotoxicity, intracellular transit and immune response induced by two subcutaneous (sc) administrations (days 0 and 21) with BSA entrapped in ARC made of TPL either form BM (ARC-BM) and from GC (ARC-GC) at 2% w/w (BSA/lipids), to C3H/HeN mice (25 microg BSA, 1.3 mg of archaeal lipids per mouse) and boosted on day 180 with 25 microg of bare BSA, were determined. RESULTS: DNA G+C content (59.5 and 61.7% mol BM and GC, respectively), 16S rDNA sequentiation, DNA-DNA hybridization, arbitrarily primed fingerprint assay and biochemical data confirmed that BM and GC isolates were two non-previously described strains of H. tebenquichense. Both multilamellar ARC mean size were 564 +/- 22 nm, with -50 mV zeta-potential, and were not cytotoxic on Vero cells up to 1 mg/ml and up to 0.1 mg/ml of lipids on J-774 macrophages (XTT method). ARC inner aqueous content remained inside the phago-lysosomal system of J-774 cells beyond the first incubation hour at 37 degrees C, as revealed by pyranine loaded in ARC. Upon subcutaneous immunization of C3H/HeN mice, BSA entrapped in ARC-BM or ARC-GC elicited a strong and sustained primary antibody response, as well as improved specific humoral immunity after boosting with the bare antigen. Both IgG1 and IgG2a enhanced antibody titers could be demonstrated in long-term (200 days) recall suggesting induction of a mixed Th1/Th2 response. CONCLUSION: We herein report the finding of new H. tebenquichense non alkaliphilic strains in Argentinean Patagonia together with the adjuvant properties of ARC after sc administration in mice. Our results indicate that archaeosomes prepared with TPL from these two strains could be successfully used as vaccine delivery vehicles.