Dexamethasone-Loaded Lipid Calcium Phosphate Nanoparticles Treat Experimental Colitis by Regulating Macrophage Polarization in Inflammatory Sites

Background

The M1/M2 polarization of intestinal macrophages exerts an essential function in the pathogenesis of ulcerative colitis (UC), which can be adjusted to alleviate the UC symptoms.

Purpose

A kind of pH-sensitive lipid calcium phosphate core-shell nanoparticles (NPs), co-loading with dexamethasone (Dex) and its water-soluble salts, dexamethasone sodium phosphate (Dsp), was constructed to comprehensively regulate macrophages in different states towards the M2 phenotype to promote anti-inflammatory effects.

Methods

Dex and Dsp were loaded in the outer lipid shell and inner lipid calcium phosphate (Cap) core of the LdCaPd NPs, respectively. Then, the morphology of NPs and methods for determining drug concentration were investigated, followed by in vitro protein adsorption, stability, and release tests. Cell experiments evaluated the cytotoxicity, cellular uptake, and macrophage polarization induction ability of NPs. The in vivo distribution and anti-inflammatory effect of NPs were evaluated through a 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced BALB/c mice ulcerative colitis model.

Results

The LdCaPd NPs showed a particle size of about 200 nm and achieved considerable loading amounts of Dex and Dsp. The in vitro and in vivo studies revealed that in the acidic UC microenvironment, the cationic lipid shell of LdCaPd underwent protonated dissociation to release Dex first for creating a microenvironment conducive to M2 polarization. Then, the exposed CaP core was further engulfed by M1 macrophages to release Dsp to restrict the pro-inflammatory cytokines production by inhibiting the activation and function of the nuclear factor kappa-B (NF-κB) through activating the GC receptor and the NF kappa B inhibitor α (I-κBα), respectively, ultimately reversing the M1 polarization to promote the anti-inflammatory therapy.

Conclusion

The LdCaPd NPs accomplished the sequential release of Dex and Dsp to the UC site and the inflammatory M1 macrophages at this site, promoting the regulation of macrophage polarization to accelerate the remission of UC symptoms.

Development of Guar Gum-Pectin-Based Colon Targeted Solid Self-Nanoemulsifying Drug Delivery System of Xanthohumol

Present study deciphers development of oral polysaccharide-based colon targeted solid self-nanoemulsifying drug delivery system (S-SNEDDS) of xanthohumol (XH). Several studies have shown that XH has anti-inflammatory and antioxidant properties, suggesting that it could be a good candidate for the treatment of colorectal diseases (CRD). Despite its potential, XH has a low aqueous solubility. As a result, its bioavailability is constrained by the dissolution rate. The liquid (L)-SNEDDS was constituted using Labrafac PG as oil, Tween 80 as surfactant and Transcutol P as co-surfactant. The L-SNEDDS was then adsorbed onto the surface of guar gum and pectin and developed into S-SNEDDS powder. Ternary phase diagram was used to optimize the process of developing L-SNEDDS. The formulation showed mean droplet size of 118.96 ± 5.94 nm and zeta potential of -19.08 ± 0.95 mV and drug loading of 94.20 ± 4.71%. Dissolution studies carried out in medium containing rat caecal contents (RCC) represented the targeted release of S-SNEDDS powder. It was observed that S-SNEDDS showed less than 10% release XH in initial 5 h and rapid release occurred between the 5th and 10th hour. Results of cytotoxicity studies revealed good cytotoxicity of XH loaded S-SNEDDS for Caco2 cells as compared to raw-XH.