Innate immune cell activation by adjuvant AS01 in human lymph node explants is age independent
Vicki V. Stylianou, … , Kerrie J. Sandgren, Anthony L. Cunningham
Vicki V. Stylianou, … , Kerrie J. Sandgren, Anthony L. Cunningham
Published September 24, 2024
Citation Information: J Clin Invest. 2024;134(22):e174144. https://doi.org/10.1172/JCI174144.
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Research Article Immunology Vaccines

Innate immune cell activation by adjuvant AS01 in human lymph node explants is age independent

Abstract

Vaccine adjuvants are thought to work by stimulating innate immunity in the draining lymph node (LN), although this has not been proven in humans. To bridge the data obtained in animals to humans, we have developed an in situ human LN explant model to investigate how adjuvants initiate immunity. Slices of explanted LNs were exposed to vaccine adjuvants and revealed responses that were not detectable in LN cell suspensions. We used this model to compare the liposome-based AS01 with its components, monophosphoryl lipid A (MPL) and QS-21, and TLR ligands. Liposomes were predominantly taken up by subcapsular sinus–lining macrophages, monocytes, and DCs. AS01 induced DC maturation and a strong proinflammatory cytokine response in intact LN slices but not in dissociated cell cultures, in contrast to R848. This suggests that the onset of the immune response to AS01 required a coordinated activation of LN cells in time and space. Consistent with the robust immune response observed in older adults with AS01-adjuvanted vaccines, the AS01 response in human LNs was independent of age, unlike the response to R848. This human LN explant model is a valuable tool for studying the mechanism of action of adjuvants in humans and for screening new formulations to streamline vaccine development.

Authors

Vicki V. Stylianou, Kirstie M. Bertram, Van Anh Vo, Elizabeth B. Dunn, Heeva Baharlou, Darcii J. Terre, James Elhindi, Elisabeth Elder, James French, Farid Meybodi, Stéphane T. Temmerman, Arnaud M. Didierlaurent, Margherita Coccia, Kerrie J. Sandgren, Anthony L. Cunningham

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Figure 1

Human LN explant model for studying vaccine adjuvants in situ.

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Human LN explant model for studying vaccine adjuvants in situ. (A) Fat i...
(A) Fat is trimmed from human LNs, which are then sliced longitudinally and placed cut-face down on gel foam soaked in culture medium. For adjuvant exposure via the most physiological route (i.e., via the afferent lymph), a cloning cylinder is glued to the capsule of the LN and the adjuvant applied within this. For maximum cellular exposure, LN slices are bathed in the adjuvant. (B) Flow cytometric gating strategy used to identify LN cell populations, including resident and migratory (outlined) DC populations. (C) Viability of LN lymphocyte and myeloid cell populations following in situ culturing (n = 4 for 0-, 24-, 48-, and 72-hour time points; n = 1 for 8- and 96-hour time points) was measured by flow cytometry. The median with the IQR for available donors is shown for each cell subset at each time point. (D) Frequency of cell populations within fresh, uncultured LN with a comparison between donors aged 50 YOA or younger (filled boxes, n = 12) and older than 65 YOA (open boxes, n = 22). The median and IQR are shown for lymphocyte (B, T, NK, NK-T) and myeloid (HLA-DR+) cell populations as a percentage of live, CD45+ immune cells and (E) macrophage, monocyte, and DC subsets within the LN as a percentage of live, CD45+, CD19–, CD3–, CD56–, and HLA-DR+ myeloid cells. All subset comparisons between LNs from young or older individuals were not significant by Mann-Whitney U test using the Bonferroni-Dunn correction method for multiple comparisons. Macs, macrophages; Monos, monocytes; dcDC2, dermud-derived conventional DC type 2; Lang, langerin; LC, Langerhans cell.