Key Points

RNA-seq profiling delineates cDC1 responses to extracellular stimuli.

Poly(I:C) activates autocrine IFN-I signaling in cDC1s.

IL-10 inhibits autocrine IFN-I responses in cDC1s via STAT3.

Abstract

Type I conventional dendritic cells (cDC1s) are an essential Ag-presenting population required for generating adaptive immunity against intracellular pathogens and tumors. While the transcriptional control of cDC1 development is well understood, the mechanisms by which extracellular stimuli regulate cDC1 function remain unclear. We previously demonstrated that the cytokine-responsive transcriptional regulator STAT3 inhibits polyinosinic:polycytidylic acid [poly(I:C)]-induced cDC1 maturation and cDC1-mediated antitumor immunity in murine breast cancer, indicating an intrinsic, suppressive role for STAT3 in cDC1s. To probe transcriptional mechanisms regulating cDC1 function, we generated novel RNA sequencing datasets representing poly(I:C)-, IL-10–, and STAT3-mediated gene expression responses in murine cDC1s. Bioinformatics analyses indicated that poly(I:C) stimulates multiple inflammatory pathways independent of STAT3, while IL-10–activated STAT3 uniquely inhibits the poly(I:C)-induced type I IFN (IFN-I) transcriptional response. We validated this mechanism using purified cDC1s deficient for STAT3 or IFN signaling. Our data reveal IL-10–activated STAT3 suppresses production of IFN-β and IFN-γ, accrual of tyrosine phosphorylated STAT1, and IFN-stimulated gene expression in cDC1s after poly(I:C) exposure. Moreover, we found that maturation of cDC1s in response to poly(I:C) is dependent on the IFN-I receptor, but not the type II IFN receptor, or IFN-λ. Taken together, we elucidate an essential role for STAT3 in restraining autocrine IFN-I signaling in cDC1s elicited by poly(I:C) stimulation, and we provide novel RNA sequencing datasets that will aid in further delineating inflammatory and anti-inflammatory mechanisms in cDC1s.

Footnotes

This work was supported by the U.S. Department of Health and Human Services, National Institutes of Health (NIH), National Institute of Allergy and Infectious Diseases (R01AI109294 and R01AI133822 to S.S.W.); a Cancer Prevention and Research Institute of Texas Research Training award (RP170067 to T.T.C., N.L.D., and A.B.; RP210028 to L.M.K.); and the NIH National Cancer Institute MD Anderson Cancer Center Core grant (P30CA016672; supporting the MD Anderson South Campus Flow Cytometry Core Facility).

The online version of this article contains supplemental material.

Abbreviations used in this article:

BMbone marrowBMDMbone marrow–derived macrophagecDCconventional dendritic cellcDC1stype I conventional dendritic cellDCdendritic cellDEGdifferentially expressed geneFLT3LFLT3 ligandGSEAGene Set Enrichment AnalysisIFN-Itype I IFNIPAIngenuity Pathway AnalysisIRFIFN regulatory factorISGIFN-stimulated geneMHC IMHC class IPCAprincipal-component analysispoly(I:C)polyinosinic:polycytidylic acidPSpenicillin-streptomycinpSTAT1tyrosine phosphorylated STAT1qRT-PCRquantitative RT-PCRRNA-seqRNA sequencingTMEtumor microenvironmentReceived November 22, 2021.Accepted July 25, 2022.Copyright © 2022 by The American Association of Immunologists, Inc.