Human IL22 mRNA

Oral mRNA delivery is a promising but understudied therapeutic approach for inflammatory bowel disease (IBD). Inspired by the colon-targeting properties of ginger-derived nanoparticles (GDNPs), researchers reverse engineered lipid nanoparticles containing the three main lipids found in GDNPs. When mixed in the ratios described in GDNPs, the selected lipids self-assembled into novel lipid nanoparticles (nLNPs) in phosphate buffer. Researchers encapsulated IL-22-mRNA in nLNPs, as enhancing IL-22 expression in the colon is known to have potent anti-inflammatory effects against ulcerative colitis (UC). IL-22 mRNA-loaded nLNPs (IL-22/nLNPs) were tested to be approximately 200 nm in diameter and had a zeta potential of -18 mV. Oral administration of IL-22/nLNPs increased IL-22 protein expression levels in the colonic mucosa of mice. In an acute colitis mouse model, mice fed IL-22/nLNPs had accelerated colon healing, as evidenced by greater recovery of body weight and colon length, and decreased histological indices, colonic MPO activity, fecal lipocalin concentrations, and mRNA expression levels of proinflammatory cytokines (TNF-α, IL-6, and IL-1β). These findings suggest that reverse-engineered nLNPs are a good mRNA delivery platform for the treatment of ulcerative colitis.

Here, the researchers examined the particle size and surface zeta potential of the generated mRNA-loaded nLNPs using a dynamic light scattering device. The average diameter of nLNPs was approximately 200 nm, and the zeta potential was -29 ± 0.5 mV (Figure 1A-B). In addition, the size and zeta potential of both nLNPs and IL-22/nLNPs were maintained in PBS solution for more than 5 h (Figure 1F). Thin layer chromatography (TLC) showed clear separation of nLNP components, including DGDG, MGDG, and PA. In addition, the TLC lipid profile of nLNPs was similar to that of GDNPs (Figure 1C, right two columns). The morphology of nLNPs was examined using scanning electron microscopy (SEM). They appeared roughly spherical with a particle size of 200 nm (Figure 1D). Next, the researchers tested whether nLNPs could effectively protect the encapsulated mRNA. Agarose gel electrophoresis was performed using free IL-22 mRNA, RNase-treated IL-22 mRNA, and RNase-treated nLNPs-encapsulated IL-22 mRNA. Gel imaging showed that free IL-22 mRNA was degraded by RNase, while nLNPs-encapsulated IL-22 mRNA was not degraded (Figure 1E). In addition, although free IL-22 mRNA was unstable in simulated gastric fluid (SGF) or simulated intestinal fluid (SIF), nLNPs were able to prevent most of the encapsulated mRNA from being degraded in SGF and SIF. These findings suggest that nLNPs can protect encapsulated IL-22 mRNA, potentially delivering it to the target area.

Figure 1. Characterization of nLNPs and stability test of IL-22/nLNPs. (Sung J, et al., 2022)