(165k) Biomimetic Virus Nanoparticles for Oral Vaccine Delivery across Gut Organoid Mucosal Models

Tianjian Tong¹, Yijun Qi¹, Luke D. Bussiere³, Debarpan Dhar³, Cathy L Miller³, Chenxu Yu², Qun Wang¹*

¹Department of Chemical & Biological Engineering, ²Department of Agricultural Biosystem and Engineering, ³ Department of Vet Microbiology & Preventive Medicine, Iowa State University

Statement of Purpose: In the age of the COVID-19 pandemic, the significance of effective oral vaccines is as high as it has ever been. Compared to the intramuscular/ intravenous injection as the delivery pathway for vaccines, oral delivery through gastrointestinal mucosa has its unique advantages of high patient acceptance (e.g., no pain), easy administration, and high efficacy via triggering mucosal immunological responses. The effective oral vaccine requires high delivery efficiency across the gastrointestinal epithelia and protection of medically effective payloads (i.e., immunogens) against gastric damage [1]. In this study, hollowed artificial virus nanoparticles (AVNs: silica nanospheres and gold nanocages) with poly-l-lysine (PLL) coating and mammalian orthoreovirus cell attachment protein σ1 functionalization (NC-PLL-σ1) were explored as oral vaccine delivery vehicles (OVDVs).

Methods: To validate the effectiveness of the OVDVs as transporters and to evaluate the differences in payload protection and release with and without the PLL coating, we used the same intestinal monolayer system we reported before [2] mimic to the gastrointestinal epithelia in Figure 1. Utilizing this M cell monolayer system, we aimed to compare the capacity of both complete OVDVs (e.g., HSS-PLL-σ1) and uncoated OVDVs (e.g., HSS-σ1) to transport model payload (e.g., R6G) across the monolayer via M cell-mediated transcytosis pathway. This system serves as an excellent simulation to evaluate the potential effectiveness of the OVDVs at transporting vaccines to reach mucosal-associated lymphoid tissues (MALTs). In addition, via control of the organoid engineering process (different Rank L levels at 200 ng/mL, 100 ng/mL, and 0 ng/mL, respectively), organoid monolayers with different M cell presence were created, as shown in Figure 2. Their effects on the transport of OVDVs and delivery of the model payload were characterized.

Results: The transport of these OVDVs to mucosal lymphoid tissues could be facilitated by microfold (M-cells) mediated transcytosis (via σ1-α2–3-linked sialic acids adherence) across gastrointestinal epithelia. A model payload, PLL coating provided protection and slow-release control of rhodamine 6 G. The transport effectiveness of these OVDVs was tested on intestinal organoid mucosal models ex vivo. As shown in Figure 3, when compared with other experimental groups, the complete OVDV system (with PLL-σ1) demonstrated two significant advantages: a significantly higher transport efficiency (198% over control at 48 hrs); and protection of payloads which led to both better transport efficiency and extended-release of payloads (61% over no-coating control at 48 hrs) which could enhance vaccine efficacy. In addition, it was shown that the M cell presence in intestinal organoid monolayers (modulated by Rank L levels) was a determining factor in the transport efficiency of the OVDVs. The complete OVDVs showed great potential as effective oral vaccine and drug delivery systems.

Figure 1. Scheme: T1L σ1 functionalized OVDVs exploit the M cell transcytosis pathway. (a) Model of MRV infection of MALT. (b) Schematic of the transport of R6G loaded OVDVs nanocarriers through M cells incorporated into intestinal organoid monolayers.

Figure 2. Detection of microfold cells in 3D mouse organoids and 2D organoid-derived monolayers.

Figure 3. GNC- PLL-σ, HSS-PLL-σ1 transport total through intestinal monolayers with different Rank L levels (200 ng/mL, 100 ng/mL).

Conclusions: We report a universal setup of oral drug/vaccine delivery vehicles utilizing the σ1-M cell-mediated transcytosis pathway for payload transport across gastrointestinal epithelia, which could effectively improve oral vaccine efficacy.

References:

¹Davoudi Z, et al. Marine Drugs 2021, 19(5): 282-298.

²Tong T, et al. Nanoscale 2020, 12(30): 16339-16347.