Research ArticleIMMUNOLOGY

The pore size of mesoporous silica nanoparticles regulates their antigen delivery efficiency

See allHide authors and affiliations

Science Advances  19 Jun 2020:
Vol. 6, no. 25, eaaz4462
DOI: 10.1126/sciadv.aaz4462
  • Fig. 1 Schematic illustration of the DUMP cascade of antigen-loaded lymph node–targeting MSNs to induce adaptive immune response.

    MSNs with different pore sizes were synthesized by adjusting the concentration of tetraethyl orthosilicate (TEOS) in cyclohexane, after which the MSNs were loaded with ovalbumin (OVA) antigen (OVA@MSNs). CTAC, cetyltrimethylammonium chloride; TEA, triethanolamine; TCR, T cell receptor. After subcutaneous injection, OVA@MSNs efficiently accomplished the DUMP cascade: drainage to lymph nodes, uptake by DCs, maturating DCs, and presenting peptide–MHC I complexes to CD8+ T cells.

  • Fig. 2 Characterization of MSNs with large (MSNs-L), medium (MSNs-M), and small (MSNs-S) pores.

    (A) Hydrodynamic diameter distribution. (B) Transmission electron micrographs. Scale bars, 50 nm. (C) Nitrogen absorption-desorption isotherms. (D) Pore size distribution. (E) Small-angle x-ray scattering. (F) Zeta potential of MSNs loaded with or without OVA. (G) Encapsulation efficiency (EE) and loading capacity (LC) of OVA. (H) Release of OVA from OVA@MSNs in PBS. Asterisks indicate P values associated with comparisons between OVA@MSNs-L and OVA@MSNs-M or OVA@MSNs-S; pound signs indicate the same P ranges for comparisons between OVA@MSNs-M with OVA@MSNs-S. The significance of the results was analyzed by using one-way analysis of variance (ANOVA). *P < 0.05, **P < 0.01, and ***P < 0.001; #P < 0.05 and ##P < 0.01; ns, not significant. Data are shown as means ± SD (n = 3). All experiments were repeated two to three times.

  • Fig. 3 Cellular uptake and antigen cross-presentation of OVA@MSNs in vitro.

    (A) Relative viability of DC2.4 cells exposed to different concentrations of MSNs. (B) Uptake efficiency of OVA@MSNs by DC2.4 cells. (C) Screening of potential mechanisms of OVA@MSNs internalization by DC2.4 cells. M-β-CD, methyl-β-cyclodextrin. (D) Cross-presentation of OVA in DC2.4 cells. (E) Expression of costimulatory molecules CD86 and CD80 on bone marrow–derived DCs (BMDCs) after 18 hours of incubation with MSNs. LPS, lipopolysaccharide. Data are shown as means ± SD (n = 3). Significance of results was analyzed by using one-way ANOVA. *P < 0.05, **P < 0.01, and ***P < 0.001. All experiments were repeated two to three times.

  • Fig. 4 Targeting of draining lymph nodes and activation of lymph node–resident DCs by OVA@MSNs.

    (A) Migration of Cy5-OVA@MSNs from the injection site to draining lymph nodes in vivo, as observed using an IVIS Spectrum system. p, photon. (B) Popliteal and inguinal lymph nodes (LNs) were isolated and visualized at 36 hours after Cy5-OVA@MSNs injection. (C) Total radiant efficiency of popliteal lymph nodes at 36 hours after injection. (D) Popliteal lymph nodes were isolated at 10 hours after OVA@MSNs injection, and frozen sections were prepared and analyzed by confocal fluorescence microscopy. Scale bars, 200 μm. DAPI, 4′,6-diamidino-2-phenylindole. (E and F) Percentages of (E) CD11c+ DCs, (F) CD8a+CD11c+, or CD11b+CD11c+ DCs that were Cy5-OVA positive. (G and H) OVA@MSNs promoted expansion and activation of DCs in lymph nodes. The percentages of CD11c+ DCs in all lymph node cell populations (G) and percentage of CD86+ in CD11c+ DCs (H) at 3 days after immunization. Data are shown as means ± SD (n = 3 to 5). All experiments were repeated two to three times. Photo credit (A): Xiaoyu Hong, Key Laboratory of Drug Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, West China School of Pharmacy, Sichuan University.

  • Fig. 5 Ability of OVA@MSNs to activate immune responses.

    On days 0, 14, and 28, C57BL mice were vaccinated in the footpad with 10 μg of free OVA or 40 μg of MSNs loaded with 10 μg of OVA. Immune responses were measured on days 21, 28, and 35. (A to C) Levels of anti-OVA IgG, IgG1, and IgG2a antibodies in serum were assayed (105 dilution). OD, optical density. (D to G) Splenocytes were restimulated with OVA (100 μg/ml) or SIINFEKL (2 μg/ml) for 6 hours at 37°C; then, flow cytometry was used to determine percentages of OVA-specific (D) IL-4–producing CD4+ T cells, (E) IFN-γ–producing CD4+ T cells, (F) IFN-γ–producing CD8+ cells, and (G) TNF-α–producing CD8+ T cells. (H) Numbers of IFN-γ–secreting CD8+ T cells in the splenocytes were measured using IFN-γ ELISpot assay. SFU, spot-forming unit. (I) Percentage of OVA-specific CD8+ T cell lysis. *P < 0.05, **P < 0.01, and ***P < 0.001. Data are shown as means ± SD (n = 4 to 5).

  • Fig. 6 Tumor growth inhibition potency of MSN loading antigen and survival curve of mice.

    (A) Schematic of the experiment design. (B) Tumor growth curves and (C) Kaplan-Meier survival curves of mice immunized with free OVA and OVA@MSNs. (D) Tumor growth curves and (E) Kaplan-Meier survival curves of mice immunized with free BM+BL and BM+BL@MSNs. Results in (B) and (D) were analyzed using one-way ANOVA. Survival results in (C) and (E) were analyzed using a log-rank test. *P < 0.05, **P < 0.01, and ***P < 0.001 versus free OVA; #P < 0.05, ##P < 0.01, and ###P < 0.001 versus OVA@MSNs-S; §P < 0.05, §§P < 0.01, and §§§P < 0.001 versus OVA@MSNs-M. Data are shown as means ± SD (n = 9 to 10).

Supplementary Materials

  • Supplementary Materials

    The pore size of mesoporous silica nanoparticles regulates their antigen delivery efficiency

    Xiaoyu Hong, Xiaofang Zhong, Guangsheng Du, Yingying Hou, Yunting Zhang, Zhirong Zhang, Tao Gong, Ling Zhang, Xun Sun

    Download Supplement

    This PDF file includes:

    • Tables S1 and S2
    • Figs. S1 to S8

    Files in this Data Supplement:

Stay Connected to Science Advances

Navigate This Article