Naturally occurring intestinal nanomineral particles constituently form in the mammalian
gut and trap luminal protein and microbial components. These cargo loaded nanominerals are actively scavenged by M cells of intestinal immune follicles, such as Peyer’s
patches and are passed to antigen-presenting cells. Using peripheral blood mononuclear
cell populations as an in vitro model of nanomineral uptake and antigen presentation,
we show that monocytes avidly phagocytose nanomineral particles bearing antigen
and peptidoglycan (PGN), and that the presence of PGN within particles downregulates
their cell surface MHC class II and upregulates programmed death receptor ligand 1.
Nanomineral delivery of antigen suppresses antigen-specific CD4+ T cell responses,
an effect that is enhanced in the presence of PGN. Blocking the interleukin-10 receptor
restores CD4+ T cell responses to antigen codelivered with PGN in nanomineral form.
Using human intestinal specimens, we have shown that the in vivo nanomineral pathway
operates in an interleukin-10 rich environment. Consequently, the delivery of a dual
antigen–PGN cargo by endogenous nanomineral in vivo is likely to be important in the
establishment of intestinal tolerance, while their synthetic mimetics present a potential
delivery system for therapeutic applications targeting the modulation of Peyer’s patch
T cell responses