Immune homeostasis in the intestine is tightly controlled by FOXP3 + regulatory T cells (Tregs), defects of which are linked to the development of chronic conditions, such as inflammatory bowel disease (IBD). As a mechanism of immune evasion, several species of intestinal parasites boost Treg activity. The parasite Heligmosomoides polygyrus is known to secrete a molecule (Hp-TGM) that mimics the ability of TGF-b to induce FOXP3 expression in CD4 + T cells. The study aimed to investigate whether Hp-TGM could induce human FOXP3 + Tregs as a potential therapeutic approach for inflammatory diseases. CD4 + T cells from healthy volunteers were expanded in the presence of Hp-TGM or TGF-b. Treg induction was measured by flow cytometric detection of FOXP3 and other Treg markers, such as CD25 and CTLA-4. Epigenetic changes were detected using ChIP-Seq and pyrosequencing of FOXP3. Treg phenotype stability was assessed following inflammatory cytokine challenge and Treg function was evaluated by cellular co-culture suppression assays and cytometric bead arrays for secreted cytokines. Hp-TGM efficiently induced FOXP3 expression (> 60%), in addition to CD25 and CTLA-4, and caused epigenetic modification of the FOXP3 locus to a greater extent than TGF-b. Hp-TGM-induced Tregs had superior suppressive function compared with TGF-b-induced Tregs, and retained their phenotype following exposure to inflammatory cytokines. Furthermore, Hp-TGM induced a Treg-like phenotype in in vivo differentiated Th1 and Th17 cells, indicating its potential to reprogram memory cells to enhance immune tolerance. These data indicate Hp-TGM has potential to be used to generate stable human FOXP3 + Tregs to treat IBD and other inflammatory diseases.

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