Low-Dose Tolerance Is Mediated By The M Cell Ligand, Reovirus Protein Sigma One

Mucosal tolerance induction generally requires multiple or large antigen (Ag) doses. Since M cells have been implicated as being important for mucosal tolerance induction and because reovirus attachment protein sigma 1 (pσ1) is capable of binding microfold (M) cells, we postulated that targeting a model Ag to M cells via pσ1 could induce a state of unresponsiveness. Accordingly, a genetic fusion between ovalbumin (OVA) and the M cell ligand, reovirus pσ1, termed OVA-pσ1, was developed to enhance tolerogen uptake. When applied nasally, not parenterally, as little as a single dose of OVA-pσ1 failed to induce OVA-specific Abs even in the presence of adjuvant. Moreover, the mice remained unresponsive to peripheral OVA challenge, unlike mice given multiple nasal OVA doses that rendered them responsive to OVA. observed unresponsiveness to OVA-pσ1 could be adoptively transferred using cervical lymph node (CLN) CD4 + T cells, which failed to undergo proliferative or delayed-type hypersensitivity (DTH) responses in recipients. discern the cytokines responsible as a mechanism for this unresponsiveness, restimulation assays revealed increased production of regulatory cytokines, IL-4, IL-10, and TGF-β, with greatly reduced IL-17 and IFN-γ. induced IL-10 was derived predominantly from forkhead box P3 (FoxP3) + CD25 + CD4 + T cells. FoxP3 + CD25 + CD4 + T cells were induced in OVA-pσ1-dosed IL-10 deficient (IL-10 −/− ) mice, and despite showing increased TGF-β synthesis, these mice were responsive to OVA. These data demonstrate the feasibility of using pσ1 as a mucosal delivery platform specifically for low-dose tolerance induction.