<p>Targeted lipid nanoparticle delivery of calcitriol to human monocyte-derived macrophages in vitro and in vivo: investigation of the anti-inflammatory effects of calcitriol</p>

Abstract

Background: Vitamin D 3 possesses anti-inflammatory and modulatory properties in addition to its role in calcium and phosphate homeostasis. Upon activation, macrophages (M) can initiate and sustain pro-inflammatory cytokine production in inflammatory disorders and play a pathogenic role in certain cancers. Purpose: The main purpose of this study was to encapsulate and specifically target calcitriol to macrophages and investigate the anti-inflammatory properties of calcitriol in vitro and in vivo. Methods: In this study we have designed and developed near-infrared calcitriol PEGylated nanoparticles (PEG-LNP(Cal)) using a microfluidic mixing technique and modified lipid nanoparticles (LNPs) to target the M specific endocytic receptor CD163. We have investigated LNP cellular uptake and anti-inflammatory effect in LPS-induced M in vitro by flow cytometry, confocal microscopy and gene expression analyses. LNP pharmacodynamics, bio-distribution and organ specific LNP accumulation was also investigated in mice in vivo. Results: In vitro, we observed the specific uptake of PEG-LNP(Cal)-hCD163 in human M, which was significantly higher than the non-specific uptake of control PEG-LNP(Cal)-IgG(h) in M. Pretreatment with encapsulated calcitriol was able to attenuate intracellular TNF-expression, and M surface marker HLA-DR expression more efficiently than free calcitriol in LPS-induced M in vitro. Encapsulated calcitriol diminished mRNA gene levels of TNF-, NF-B, MCP-1 and IL-6, while upregulating IL-10. TNF-and IL-6 protein secretion also decreased. In mice, an in vivo pharmacodynamic study of PEG-LNP(Cal) showed a rapid clearance of IgG and CD163 modified LNPs compared to PEG-LNP(Cal). Antibody modified PEG-LNP(Cal) accumulated in the liver, spleen and kidney, whereas unmodified PEG-LNP(Cal) accumulation was only observed in the liver. Conclusion: Our results show that calcitriol can be effectively targeted to M. Our data confirms the anti-inflammatory properties of calcitriol and this may be a potential way to deliver high dose bioactive calcitriol to M during inflammation in vivo.

Targeting of CD163+ Macrophages in Inflammatory and Malignant Diseases

“…As an alternative to target dexamethasone to macrophages, Rafique et al [ 322 ] strengthened the anti-inflammatory effect of another steroid, calcitriol (vitamin D) on human monocytes in vitro using CD163-targeted pegylated nanoparticles loaded with calcitriol. M-CSF/ Granulocyte-macrophage colony-stimulating factor (GM-CSF) differentiated human macrophages from buffy coats were incubated with either non-targeted stealth calcitriol liposomes or stealth liposomes with CD163-antibody or control IgG for 24 h before induction of inflammation by LPS for 4 h. The CD163-targeted calcitriol treatment reduced the mRNA expression of anti-inflammatory markers and increased the expression of the pro-inflammatory cytokine, IL-10.…”

“…Therefore, the anti-inflammatory effects may not solely be attributed to the targeting of CD163. Distribution of the liposomes in vivo was investigated using Xenogen in vivo imaging system (IVIS), which revealed accumulation of CD163-targeted liposomes in the liver within 15 min while non-targeted liposomes circulated in the blood stream for more than three and a half hours [ 322 ]. This might indicate that CD163-targeting of calcitriol is favorable and specific as Kupffer cells express CD163.…”

Nanoparticles Targeting Macrophages as Potential Clinical Therapeutic Agents Against Cancer and Inflammation

“…Rafique et al encapsulated calcitriol into LNPs and developed near-infrared calcitriol PEGylated NPs [PEG-LNP(Cal)] by a microfluidic mixing technique. The results showed that calcitriol can be effectively targeted to macrophages (69). Nanotechnology systems for the targeted delivery of drugs to TAMs are effective methods for mitigating tumor promotion (46).…”

Surface Plasmon Resonance as a Characterization Tool for Lipid Nanoparticles Used in Drug Delivery

“…SPR experiments have been defining in the obtention of decorated liposomes with high affinity to amyloid-β peptide (Gobbi et al, 2010 ; Mourtas et al, 2011 ; Gregori et al, 2017 ), contributing to the development of very promising vectors for the targeted delivery of potential new diagnostic and therapeutic molecules for Alzheimer's disease. SPR sensing based on surface immobilization of the target protein onto Au- CMD chips ( Figure 1E , left) has also contributed to the elucidation of the interplay of decorated liposomes or SLNs and membrane proteins that are overexpressed in malignant tissues (Nielsen et al, 2002 ; Terada et al, 2007 ; Mizrahy et al, 2011 ; Shi et al, 2015a ; Huang et al, 2019 ), in disease-supporting macrophages (Etzerodt et al, 2012 ; Rafique et al, 2019 ) or in T-cells involved in autoimmune diseases (Ding et al, 2015 ). Moreover, SPR studies based on immobilized liposomes ( Figure 1E , right) have shed light on the complex mechanism for the interaction of lectins with glycoliposomes specially designed to target sugar-binding proteins (Tamiaki et al, 2006 ; Sandoval-Altamirano et al, 2017 ).…”