T follicular helper cells in human efferent lymph retain lymphoid characteristics
Laura A. Vella, … , Michael R. Betts, E. John Wherry
Laura A. Vella, … , Michael R. Betts, E. John Wherry
Published August 1, 2019; First published July 2, 2019
Citation Information: J Clin Invest. 2019;129(8):3185-3200. https://doi.org/10.1172/JCI125628.
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Research Article Immunology

T follicular helper cells in human efferent lymph retain lymphoid characteristics

Abstract

T follicular helper cells (Tfh), a subset of CD4+ T cells, provide requisite help to B cells in the germinal centers (GC) of lymphoid tissue. GC Tfh are identified by high expression of the chemokine receptor CXCR5 and the inhibitory molecule PD-1. Although more accessible, blood contains lower frequencies of CXCR5+ and PD-1+ cells that have been termed circulating Tfh (cTfh). However, it remains unclear whether GC Tfh exit lymphoid tissues and populate this cTfh pool. To examine exiting cells, we assessed the phenotype of Tfh present within the major conduit of efferent lymph from lymphoid tissues into blood, the human thoracic duct. Unlike what was found in blood, we consistently identified a CXCR5-bright PD-1–bright (CXCR5BrPD-1Br) Tfh population in thoracic duct lymph (TDL). These CXCR5BrPD-1Br TDL Tfh shared phenotypic and transcriptional similarities with GC Tfh. Moreover, components of the epigenetic profile of GC Tfh could be detected in CXCR5BrPD-1Br TDL Tfh and the transcriptional imprint of this epigenetic signature was enriched in an activated cTfh subset known to contain vaccine-responding cells. Together with data showing shared TCR sequences between the CXCR5BrPD-1Br TDL Tfh and cTfh, these studies identify a population in TDL as a circulatory intermediate connecting the biology of Tfh in blood to Tfh in lymphoid tissue.

Authors

Laura A. Vella, Marcus Buggert, Sasikanth Manne, Ramin S. Herati, Ismail Sayin, Leticia Kuri-Cervantes, Irene Bukh Brody, Kaitlin C. O’Boyle, Hagop Kaprielian, Josephine R. Giles, Son Nguyen, Alexander Muselman, Jack P. Antel, Amit Bar-Or, Matthew E. Johnson, David H. Canaday, Ali Naji, Vitaly V. Ganusov, Terri M. Laufer, Andrew D. Wells, Yoav Dori, Maxim G. Itkin, Michael R. Betts, E. John Wherry

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Figure 6

Epigenetic signature of GC Tfh can be traced into CXCR5BrPD-1Br TDL Tfh and is associated with transcriptional events in activated cTfh in blood.

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Epigenetic signature of GC Tfh can be traced into CXCR5BrPD-1Br TDL Tfh ...
(A) Heatmap of OCRs differentially accessible in CXCR5BrPD-1Br Tfh LNs and TDL compared with CXCR5DimPD-1Dim Tfh. (B) ATAC-Seq tracks of the BCL6 and MAF loci in CXCR5BrPD-1Br Tfh (red, merged from 3 samples for each population) and CXCR5DimPD-1Dim Tfh (teal, merged from 2 samples from each population). (C) Correlation plot of log fold changes in ATAC-Seq and RNA-Seq data sets. (D) ATAC-Seq tracks of loci defined in C, with cTfh in blue. Shaded bars are loci differentially accessible in CXCR5BrPD-1Br versus CXCR5DimPD-1Dim Tfh. (E) Percentage of CXCR5BrPD-1Br TDL Tfh producing IL-21 before and after stimulation with PMA/ionomycin. (F) Gating strategy for TCR sequencing sort (n = 4 paired samples). (G) TCR overlap between the Tfh populations as indicated in F. (H) Frequency of CDR3 sequences of overlapping clones between Tfh populations (TDL and blood) and gates (bright and dim) in a representative patient. (I) GSEA of transcriptional signatures from tonsil GC Tfh versus tonsil non-GC Tfh (GSE50391) compared with differentially expressed genes in ICOS+CD38+ versus ICOS–CD38– cTfh. Normalized enrichment scores, FDR, and selected leading edge genes noted on plot. (J) Unique peaks in GC Tfh versus non-GC Tfh. (K) Genomic distribution of GC Tfh unique peaks. (L) GREAT analysis to identify GO biologic processes within GC Tfh unique peaks. (M) Homer Motif prediction to identify known transcription factor–binding sites enriched in GC Tfh unique peaks. (N) Radar plot of GSEA enrichment for ICOS+CD38+ versus ICOS–CD38– cTfh signature using gene sets derived from unique peaks in GC Tfh, non-GC Tfh, CXCR5BrPD-1Br TDL Tfh, and CXCR5DimPD-1Dim Tfh as well as the overlap between the cell types as indicated. NES noted for each ring. *P < 0.05; **P < 0.01, paired 2-tailed t tests (E and G).