Ogunshola, F. J. | Search bioRxiv

bioRxiv2026

Duration of Initial Viremia Modulates Functional Properties of HIV-specific T Cell Receptors

Virus-specific CD8+ T cells are crucial in controlling chronic human viral infections such as HIV-1, but the effect of persistent antigen exposure on T cell repertoire formation is not well understood. In this study, we examined epitope-specific CD8+ T cell repertoires in people living with HIV-1, where duration of viremia following hyperacute infection was modulated by the time of initiation of continuous suppressive antiretroviral therapy (ART). After ART-induced undetectable viremia in persons expressing the same HLA class I allele, we analyzed the impact of early (n=6) versus delayed (n=6) ART initiation on the clonotypic composition, clonotypic cross-reactivity, functional avidity and memory differentiation profile of the HIV-specific T cell repertoire restricted by HLA-B*58:01. Using a panel of barcoded tetramers, we mapped T cell receptor (TCR) clonotypes specific for three dominant epitopes and their variants. Both groups exhibited polyclonal TCR repertoires with evidence of cross-reactivity, which was significantly enriched in donors with prolonged antigen exposure. Within this cohort, broadly cross-reactive clonotypes capable of recognizing all autologous variants were identified, but these were rare (<1%). Early ART initiation preserved repertoires characterized by higher-avidity TCRs and a relative enrichment of transitional memory CD8+ T cell subsets. These functional differences were not associated with differences in TRBV gene sharing, indicating that ART timing shapes repertoire quality and memory differentiation without altering TRBV gene bias. These findings demonstrate how antigen suppression dynamics differentially shape the breadth, functional sensitivity, and memory composition of the HIV-specific TCR repertoire, with implications for T cell-directed immunotherapies and HIV cure strategies. One Sentence SummaryThe duration of viral antigen exposure during early HIV infection shapes the functional quality, breadth, and memory composition of virus-specific CD8 T cell receptor repertoires. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=77 SRC="FIGDIR/small/702605v1_ufig1.gif" ALT="Figure 1"> View larger version (17K): org.highwire.dtl.DTLVardef@9a5a6dorg.highwire.dtl.DTLVardef@1a6bbdaorg.highwire.dtl.DTLVardef@17707e8org.highwire.dtl.DTLVardef@1a84d9e_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2020

CXCR5 gene expression in human lymph node CD8+ T cells is regulated by DNA methylation and nucleosomal occupancy

CD8+ T cells play an important role in viral and tumour control. However, in human lymph nodes (LNs), only a small subset of CD8+ T cells called follicular CD8+ T cells (fCD8s) expresses CXCR5, the chemokine receptor required for cell migration into B cell follicles, thought to promote immune evasion. Here we obtained LNs from HIV infected persons to investigate regulation of CXCR5 expression in lymphoid CD8+ T cells, and compared this to the more abundant CXCR5 expressing T follicular CD4+ helper cells (GCTfh). Our results show that DNA hypermethylation and closed chromatin at the transcriptional start site (TSS) prevent CXCR5 expression in non-fCD8s. We also found that greater nucleosomal density at the CXCR5 TSS could be responsible for reduced CXCR5 expression in fCD8s relative to GCTfh. Together, these data provide critical insights into both the underlying molecular mechanisms that repress CXCR5 expression in non-fCD8s and the plausible mechanism responsible for the low CXCR5 expression in fCD8s, with implications for HIV cure strategies. Author SummaryA paucity of CD8+ T cells that express CXCR5, the chemokine receptor critical for entering the B cell follicles of secondary lymphoid tissues have recently been described. Animal studies have revealed transcriptional networks that govern the expression of CXCR5 in CD8+ T cells. However, it is not known if similar or additional networks regulate the expression of CXCR5 in human CD8+ T cells. In this study, we demonstrated that DNA methylation coupled with chromatin compaction at the transcriptional start site (TSS) of CXCR5 gene prevent the expression CXCR5 in human CD8+ T cells. In addition, we observed greater nucleosomal occupancy at the TSS of CXCR5 gene which could impact expression levels of CXCR5 in human CXCR5+CD8+ T cells. This study revealed multitiered epigenetic mechanisms that repress CXCR5 expression in human CD8+ T cells, with implications for HIV cure strategy or eradication of B cell-derived tumours.

genetics↗