Single cell RNA-seq of IL-10-producing CD4 T cells during chronic LCMV infection
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ABSTRACT: During chronic viral infection, the inflammatory function of CD4 T cells becomes gradually attenuated. Concurrently, Th1 cells progressively acquire the capacity to secrete the cytokine IL-10, a potent suppressor of antiviral T cell responses. To determine the transcriptional changes that underlie this T cell adaption process, we applied a single-cell RNA-sequencing approach and assessed the heterogeneity of IL-10-expressing CD4 T cells during chronic infection. Unexpectedly, our analyses revealed an IL-10-producing population with a robust Tfh-signature. Using IL-10 and IL-21 double-reporter mice, we further demonstrate that IL-10+IL-21+co-producing Tfh cells arise predominantly during chronic but not acute LCMV infection. Importantly, depletion of IL-10+IL-21+co-producing CD4 T cells or deletion of Il10 specifically in Tfh cells resulted in impaired humoral immunity and viral control. Mechanistically, B cell-intrinsic IL-10 signaling was required for sustaining germinal center reactions. Lastly, we demonstrate that IL-27 and type I IFNs differentially regulate the formation of this protective IL-10-producing Tfh subset. Thus, our findings elucidate a critical role for Tfh-derived IL-10 in promoting humoral immunity during persistent viral infection.
Project description:During chronic viral infection, the inflammatory function of CD4 T cells becomes gradually attenuated. Concurrently, Th1 cells progressively acquire the capacity to secrete the cytokine IL-10, a potent suppressor of antiviral T cell responses. To determine the transcriptional changes that underlie this T cell adaption process, we applied a single-cell RNA-sequencing approach and assessed the heterogeneity of IL-10-expressing CD4 T cells during chronic infection. Unexpectedly, our analyses revealed an IL-10-producing population with a robust Tfh-signature. Using IL-10 and IL-21 double-reporter mice, we further demonstrate that IL-10+IL-21+co-producing Tfh cells arise predominantly during chronic but not acute LCMV infection. Importantly, depletion of IL-10+IL-21+co-producing CD4 T cells or deletion of Il10 specifically in Tfh cells resulted in impaired humoral immunity and viral control. Mechanistically, B cell-intrinsic IL-10 signaling was required for sustaining germinal center reactions. Lastly, we demonstrate that IL-27 and type I IFNs differentially regulate the formation of this protective IL-10-producing Tfh subset. Thus, our findings elucidate a critical role for Tfh-derived IL-10 in promoting humoral immunity during persistent viral infection.
Project description:T follicular helper cells (TFH) are critical for the development and maintenance of germinal centers (GC) and humoral immune responses. During chronic HIV/SIV infection TFH accumulate, possibly as a result of antigen persistence. The HIV/SIV-associated TFH expansion may also reflect lack of regulation by suppressive follicular regulatory CD4+ T-cells (TFR). TFR are natural regulatory T-cells (TREG) that migrate into the follicle and, similarly to TFH, up-regulate CXCR5, Bcl-6, and PD1. Here we identified TFR as CD4+CD25+FoxP3+CXCR5+PD1hiBcl-6+ within lymph nodes of rhesus macaques (RM) and confirmed their localization within the GC by immunohistochemistry. RNA sequencing showed that TFR exhibit a distinct transcriptional profile with shared features of both TFH and TREG, including intermediate expression of FoxP3, Bcl-6, PRDM1, IL-10, and IL-21. In healthy, SIV-uninfected RM, we observed a negative correlation between frequencies of TFR and both TFH and GC B-cells as well as levels of CD4+ T-cell proliferation. Following SIV infection, the TFR/TFH ratio was reduced with no change in the frequency of TREG or TFR within the total CD4+ T-cell pool. Finally, we examined whether higher levels of direct virus infection of TFR were responsible for their relative depletion post-SIV infection. We found that TFH, TFR and TREG sorted from SIV- infected RM harbor comparable levels of cell-associated viral DNA. Our data suggests that TFR may contribute to the regulation and proliferation of TFH and GC B-cells in vivo and that a decreased TFR/TFH ratio in chronic SIV infection may lead to unchecked expansion of both TFH and GC B-cells. TFR, TFH, TREG and bulk CD4 cells were sorted from spleens of 5 uninfected and 5 infected RM.
Project description:T follicular helper cells (TFH) are critical for the development and maintenance of germinal centers (GC) and humoral immune responses. During chronic HIV/SIV infection TFH accumulate, possibly as a result of antigen persistence. The HIV/SIV-associated TFH expansion may also reflect lack of regulation by suppressive follicular regulatory CD4+ T-cells (TFR). TFR are natural regulatory T-cells (TREG) that migrate into the follicle and, similarly to TFH, up-regulate CXCR5, Bcl-6, and PD1. Here we identified TFR as CD4+CD25+FoxP3+CXCR5+PD1hiBcl-6+ within lymph nodes of rhesus macaques (RM) and confirmed their localization within the GC by immunohistochemistry. RNA sequencing showed that TFR exhibit a distinct transcriptional profile with shared features of both TFH and TREG, including intermediate expression of FoxP3, Bcl-6, PRDM1, IL-10, and IL-21. In healthy, SIV-uninfected RM, we observed a negative correlation between frequencies of TFR and both TFH and GC B-cells as well as levels of CD4+ T-cell proliferation. Following SIV infection, the TFR/TFH ratio was reduced with no change in the frequency of TREG or TFR within the total CD4+ T-cell pool. Finally, we examined whether higher levels of direct virus infection of TFR were responsible for their relative depletion post-SIV infection. We found that TFH, TFR and TREG sorted from SIV- infected RM harbor comparable levels of cell-associated viral DNA. Our data suggests that TFR may contribute to the regulation and proliferation of TFH and GC B-cells in vivo and that a decreased TFR/TFH ratio in chronic SIV infection may lead to unchecked expansion of both TFH and GC B-cells.
Project description:CD4 T cell help is critical for both the generation and maintenance of germinal centers, and T follicular helper (TFH) cells are the CD4 T cell subset required for this process. SAP (SH2D1A) expression in CD4 T cells is essential for germinal center development. However, SAP-deficient mice have only a moderate defect in TFH differentiation as defined by common TFH surface markers. CXCR5+ TFH cells are found within the germinal center as well as along the boundary regions of T/B cell zones. Here we show that germinal center associated T cells (GC TFH) can be identified by their co-expression of CXCR5 and the GL7 epitope, allowing for phenotypic and functional analysis of TFH and GC TFH populations. Here we show GC TFH are a functionally discrete subset of further polarized TFH cells, with enhanced B cell help capacity and a specialized ability to produce IL-4 in a TH2-independent manner. Strikingly, SAP-deficient mice have an absence of the GC TFH subset and SAP- TFH are defective in IL-4 and IL-21 production. We further demonstrate that SLAM (Slamf1, CD150), a surface receptor that utilizes SAP signaling, is specifically required for IL-4 production by GC TFH. GC TFH cells require IL-4 and IL-21 production for optimal help to B cells. These data illustrate complexities of SAP-dependent SLAM family receptor signaling, revealing a prominent role for SLAM receptor ligation in IL-4 production by germinal center CD4 T cells but not in TFH and GC TFH differentiation. Analysis of in vivo polyclonal GC Tfh vs Tfh vs Non-Tfh eight days after LCMV viral infection. Analysis of in vivo follicular helper CD4 T cells (CXCR5high GL7low), versus germinal center follicular helper CD4 T cells (CXCR5hi GL7hi), versus non-follicular helper CD4 T cells (CXCR5low) eight days after viral infection.
Project description:Epigenetic changes, including histone methylation, control T cell differentiation and memory formation, though the enzymes that mediate these processes are not clear. We show that UTX, a histone H3 lysine 27 (H3K27) demethylase, promotes the generation of T follicular helper (Tfh) cells, a CD4+ T cell subset essential for B cell antibody generation and clearance of chronic viral infections. Mice with T cell specific UTX deletion (UTX TKO mice) had fewer Tfh cells, showed defective germinal center formation, lacked virus-specific IgG production, and were unable to resolve chronic lymphocytic choriomeningitis virus infection. In UTX TKO T cells, decreased expression of IL-6R±, and other Tfh-related loci, was associated with increased H3K27 methylation. Additionally, Turner Syndrome subjects, who are predisposed to chronic ear infections, have reduced UTX expression in immune cells and decreased Tfh frequency. Thus, we identify a critical link between UTX in T cells and immunity to infection. Mice were infected with chronic LCMV and sorted for Tfh on day 21 pi (sorted for: CD4+CXCR5+CD62Llo T cell). ChIP-Seq and RNA-Seq on WT and Utx KO cells.
Project description:Interleukin (IL)-10 is an immunosuppressive cytokine that signals through STAT3 to regulate T follicular helper cell (TFH) differentiation and germinal center formation. In SIV-infected macaques, levels of IL-10 in plasma and lymph node (LN) are induced by infection and not normalized with ART. During chronic infection, plasma IL-10 and transcriptomic signatures of IL-10 signaling were significantly correlated with the cell-associated SIV-DNA content within LN CD4+ memory subsets, including TFH, and predicted the frequency of CD4+ TFH and their cell- associated SIV-DNA content during ART, respectively. Notably, in ART-treated RMs, cells harboring SIV-DNA by DNAscope were preferentially found in the LN B-cell follicle in close proximity to IL-10. Finally, we demonstrate that the in vivo neutralization of soluble IL-10 in ART-treated, SIV-infected macaques significantly reduces B cell follicle maintenance and, by extension, cellular sites of viral persistence, including LN TFH and memory CD4+ T-cells expressing PD-1 and CTLA-4. Thus, these data support a role for IL-10 in maintaining a pool of target cells in lymphoid tissue that serve as a niche for viral persistence. Targeting IL-10 signaling to impair CD4+ T-cell survival and improve antiviral immune responses may represent a novel approach to limit viral persistence in ART-suppressed people living with HIV.
Project description:Interleukin (IL)-10 is an immunosuppressive cytokine that signals through STAT3 to regulate T follicular helper cell (TFH) differentiation and germinal center formation, which we propose acts as a determinant of HIV/SIV persistence. In SIV-infected macaques, levels of IL-10 in plasma and lymph node (LN) are induced by infection and not normalized with ART. During chronic infection, plasma IL-10 and transcriptomic signatures of IL-10 signaling were significantly correlated with the cell-associated SIV-DNA content within LN CD4+ memory subsets, including TFH, and predicted the frequency of CD4+ TFH and their cell-associated SIV-DNA content during ART, respectively. Notably, in ART-treated RMs, cells harboring SIV-DNA by DNAscope were preferentially found in the LN B-cell follicle in close proximity to IL-10. Finally, we demonstrate that the in vivo neutralization of soluble IL-10 in ART-treated, SIV-infected macaques significantly reduces B cell follicle maintenance and, by extension, cellular sites of viral persistence, including LN TFH and memory CD4+ T-cells expressing PD-1 and CTLA-4. Thus, these data support a role for IL-10 in maintaining a pool of target cells in lymphoid tissue that serve as a niche for viral persistence. Targeting IL-10 signaling to impair CD4+ T-cell survival and improve antiviral immune responses may represent a novel approach to limit viral persistence in ART-suppressed people living with HIV.
Project description:CD4 T cell help is critical for both the generation and maintenance of germinal centers, and T follicular helper (TFH) cells are the CD4 T cell subset required for this process. SAP (SH2D1A) expression in CD4 T cells is essential for germinal center development. However, SAP-deficient mice have only a moderate defect in TFH differentiation as defined by common TFH surface markers. CXCR5+ TFH cells are found within the germinal center as well as along the boundary regions of T/B cell zones. Here we show that germinal center associated T cells (GC TFH) can be identified by their co-expression of CXCR5 and the GL7 epitope, allowing for phenotypic and functional analysis of TFH and GC TFH populations. Here we show GC TFH are a functionally discrete subset of further polarized TFH cells, with enhanced B cell help capacity and a specialized ability to produce IL-4 in a TH2-independent manner. Strikingly, SAP-deficient mice have an absence of the GC TFH subset and SAP- TFH are defective in IL-4 and IL-21 production. We further demonstrate that SLAM (Slamf1, CD150), a surface receptor that utilizes SAP signaling, is specifically required for IL-4 production by GC TFH. GC TFH cells require IL-4 and IL-21 production for optimal help to B cells. These data illustrate complexities of SAP-dependent SLAM family receptor signaling, revealing a prominent role for SLAM receptor ligation in IL-4 production by germinal center CD4 T cells but not in TFH and GC TFH differentiation. Analysis of in vivo antigen-specific (LCMV-specific, SMARTA TCR transgenic) WT and Sh2d1a-/- follicular helper CD4 T cells (CXCR5high),versus non-follicular helper CD4 T cells (CXCR5low), eight days after viral infection.
Project description:Follicular helper T (Tfh) cells are necessary for germinal center B cell maturation during primary immune responses; however, the T cells that promote humoral recall responses via memory B cells are less well defined. We herein characterize a human tonsillar CD4+ T cell subset with this function. These cells are similar to Tfh cells in terms of expression of the chemokine receptor CXCR5 and the inhibitory receptor PD-1, interleukin (IL)-21 secretion, and expression of the transcription factor BCL6; however, unlike Tfh cells that are located within the B cell follicle and germinal center, they reside at the border of the T cell zone and the B cell follicle in proximity to memory B cells, a position dictated by their unique chemokine receptor expression. They promote memory B cells to produce antibodies via CD40 ligand, IL-10, and IL-21. Our results reveal a unique extrafollicular CD4+ T cell subset in human tonsils, which specialize in promoting T cell-dependent humoral recall responses.
Project description:CD4+ T cell-derived interleukin 21 (IL-21) sustains CD8+ T cell responses during chronic viral infection, but the helper subset that confers this protection remains unclear. Here, we applied scRNA and ATAC-seq approaches to determine the heterogeneity of IL-21+CD4+ T cells during LCMV clone 13 infection.