Non-canonical IL-2 signaling facilitates peripheral regulatory T cell differentiation

Meecham, A.; Kim, S. H. J.; Fernandes de Lima, M. H.; Tang, M.; Liao, B.; Chan, S.; Lee, H.-s.; Lu, L.-F.; Zhang, Z.; Jefferies, C.; Guma, M.; Lopez-Ramirez, M.-A.; Ginsberg, M. H.

doi:10.64898/2026.10.07.756301

bioRxiv · 10.64898/2026.10.07.756301

Non-canonical IL-2 signaling facilitates peripheral regulatory T cell differentiation

Meecham, A.·Kim, S. H. J.·Fernandes de Lima, M. H.·Tang, M.·Liao, B.·Chan, S.·Lee, H.-s.·Lu, L.-F.·Zhang, Z.·Jefferies, C.·Guma, M.·Lopez-Ramirez, M.-A.·Ginsberg, M. H.

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Abstract

Non-canonical IL-2 signaling, termed Monoclonal antibody or Matrix-directed Alternative Cytokine Signaling (MACS), is mediated by a CD25-chemokine receptor complex and operates in concert with the canonical JAK-STAT5 pathway; however, its role in T cell homeostasis remains poorly defined. Here, we uncover a role for MACS in regulatory T cell (Treg) differentiation and functional specification. We generated Il2E66K/E66K mice in which CD25-CCR7 assembly is disrupted and IL-2-induced STAT5 phosphorylation is preserved. Immunophenotyping analysis by flow cytometry revealed that MACS deficiency reduces the accumulation of Nrp1- Foxp3+ Tregs in gut-associated lymphoid tissues from 24-weeks-old Il2E66K/E66K mutant mice. Single-cell transcriptomics, functional suppression assays, and in vitro differentiation revealed that MACS engagement drives Treg differentiation and sustains effector Treg programs - marked by robust IL-10 expression - in part via an AP-1-dependent transcriptional network. These findings establish IL-2 MACS as a distinct signal directing peripheral immune tolerance and highlight a potential node for targeted immunomodulation.

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Meecham, A., Kim, S. H. J., Fernandes de Lima, M. H., Tang, M., Liao, B., Chan, S., Lee, H.-s., Lu, L.-F., Zhang, Z., Jefferies, C., Guma, M., Lopez-Ramirez, M.-A., Ginsberg, M. H.. 2026-10-14. Non-canonical IL-2 signaling facilitates peripheral regulatory T cell differentiation. https://doi.org/10.64898/2026.10.07.756301

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