Figure 9.

Summary of the pathway through which MPO/BAY DCs attenuate anti-MPO GN. DCs are (1) treated with BAY which inhibits NFκB and causes upregulation of ICOSL, and (2) exposed to MPO so they can take it up and present it to T cells. These DCs interact with MPO-specific CD4⁺Foxp3⁺ Tregs, and through the ICOSL/ICOS pathway, cause Treg proliferation and activation (upregulation of Foxp3, CTLA4, TNFR2, and IL-10). MPO/BAY DC-induced Tregs then suppress MPO-specific immunity, including CD4 and CD8 T cells, as well as B cells, via IL-10, to attenuate anti-MPO GN. TCR, T cell receptor.