Make It Simple: (SR-A1+TLR7) Macrophage Targeted NANOarchaeosomes

Abstract

Hyperhalophilic archaebacteria exclusively produce sn2,3 diphytanylglycerol diether archaeolipids, unique structures absent in bacteria and eukaryotes. Nanovesicles made of archaeolipids known as nanoarchaeosomes (nanoARC), possess highly stable bilayers, some of them displaying specific targeting ability. Here we hypothesize that nanoARC made from Halorubrum tebenquichense archaebacteria, may constitute efficient carriers for the TLR7 agonist imiquimod (IMQ). NanoARC-IMQ takes advantage of the intense interaction between IMQ and the highly disordered, poorly fluid branched archaeolipid bilayers, rich in archaeol analog of methyl ester of phosphatidylglycerophosphate (PGP-Me), a natural ligand of scavenger receptor A1 (SR-A1). This approach lacks complex manufacture steps required for bilayers labeling, enabling future analytical characterization, batch reproducibility, and adaptation to higher scale production. SR-A1 mediated internalization of particulate material is mostly targeted to macrophages and is extensive because it is not submitted to a negative feedback. A massive and selective intracellular delivery of IMQ may concentrate its effect specifically into the endosomes, where the TLR7 is expressed, magnifying its immunogenicity, at the same time reducing its systemic bioavailability, and therefore it's in vivo adverse effects. NanoARC-IMQ (600–900 nm diameter oligolamellar vesicles of ~−43 mV Z potential) were heavily loaded with IMQ at ~44 μg IMQ/mg phospholipids [~20 folds higher than the non-SR-A1 ligand soyPC liposomes loaded with IMQ (LIPO-IMQ)]. In vitro, nanoARC-IMQ induced higher TNF-α and IL-6 secretion by J774A1 macrophages compared to same dose of IMQ and same lipid dose of LIPO-IMQ. In vivo, 3 subcutaneous doses of nanoARC-IMQ+ 10 μg total leishmania antigens (TLA) at 50 μg IMQ per Balb/C mice, induced more pronounced DTH response, accompanied by a nearly 2 orders higher antigen-specific systemic IgG titers than IMQ+TLA and LIPO-IMQ. The isotype ratio of nanoARC-IMQ+TLA remained ~0.5 indicating, the same as IMQ+TLA, a Th2 biased response distinguished by a pronounced increase in antibody titers, without negative effects on splenocytes lymphoproliferation, with a potential CD8+LT induction 10 days after the last dose. Overall, this first approach showed that highly SR-A1 mediated internalization of heavily loaded nanoARC-IMQ, magnified the effect of IMQ on TLR7 expressing macrophages, leading to a more intense in vivo immune response.

Route map for the discovery and pre-clinical development of new drugs and treatments for cutaneous leishmaniasis

“…Encapsulation of drugs is another useful pharmaceutical strategy for topical CL treatment as it can offer enhanced permeation of the active drug, immunomodulatory effects, and macrophage-targeted delivery (Moreno et al, 2014), (Parra et al, 2018). Considering the complex cellular and tissue interactions of these particles, the evaluation of skin penetration requires extensive model optimization and combinations of sensitive imaging and detection methods such as Raman spectroscopy, X-ray microscopy, and flow cytometry in addition to the Franz diffusion cell assays (Vogt et al, 2014).…”

Co-aerosolized Pulmonary Surfactant and Ambroxol for COVID-19 ARDS Intervention: What Are We Waiting for?

“…DPPC has been well researched and employed for developing liposomal inhalation suspensions for targeted lung delivery and interventions including penetration of biofilms and uptake into macrophages (Chimote and Banerjee, 2010;Zhang et al, 2018). In addition, endogenous lung surfactant inspired strategies including phospholipid based nanovesicle aerosols (Joshi et al, 2015;Altube et al, 2017;Parra et al, 2018) have been reported as pulmonary compatible and efficient drug delivery platforms.…”

Fast Biofilm Penetration and Anti-PAO1 Activity of Nebulized Azithromycin in Nanoarchaeosomes

“…The combination of such unique biophysical and pharmacodynamics features of nanoARC bilayers, was recently exploited to trap difficult to dissolve in water drugs, such as the immunomodulator imiquimod. 59 Despite of the AZ: lipid w:w ratios of nanoARC-AZ (0.28) (vs (0.20) from nanoL-AZ nanoliposomes made of ordinary phospholipids used as a control) were comparable and in the order of those previously reported for other AZ vesicular formulations (~0.24 27 and ~0.23 60 ), the interaction between AZ and nanoARC bilayers was unique, and different from that occurring within nanoliposomes, where AZ remained dissolved/precipitated within the aqueous space. The  potential values, together with the structural data provided by GP, FA and SAXS, showed that AZ associated to nanoARC bilayers consisted of a combination of electrostatic interaction between negatively charged nanoARC surface and the two tertiary amines of ~ 8.7 and ~ 9.3 pKa from dicationic AZ 61 with trapping within the interface and the inner most methyl groups.…”

“…PGP-Me containing nanoARC, therefore, is naturally targeted to cells expressing SRA1. The combination of such unique biophysical and pharmacodynamic features of nanoARC bilayers was recently exploited to trap difficult-to-dissolve-in-water drugs, such as the immunomodulator imiquimod …”