Project description:We profiled the heterogeneity of virtual memory T cells and observed changes in virtual memory T cell subsets under conditions of IL-4 deficiency in mouse spleens using single-cell RNA sequencing.
Project description:The development of virtual memory CD8 T cells is dependent on IL-4, type I interferon, and IL-15. However, it remains unclear whether these cytokines individually contribute to the generation of specific subsets of virtual memory CD8 T cells. In this study, virtual memory CD8 T cells were categorized into four subsets based on Ly6C and Sca-1 expression, and their development was examined using knock-out mice lacking IFNAR1, IL-4, or IL-15Rα. Notably, both Ly6C+ Sca-1+ and Ly6C- Sca-1+ subsets were significantly reduced in the spleen of IFNAR1 knock-out mice, while the proportion of Ly6C+ Sca-1- VM CD8 T cells was reduced in IL-4-deficient mice. In IL-15Rα knock-out mice, both the Ly6C+ Sca-1- and Ly6C- Sca-1- subsets were significantly reduced. Bulk RNA sequencing analysis revealed distinct gene expression patterns in naïve cells, true memory cells, and four virtual memory cells subsets. Specifically, Ly6C+ subsets were enriched with IL-15 signal-related genes, whereas Ly6C- subsets and true memory cells were enriched for cell cycle-related genes. Functionally, the Ly6C+ subsets exhibited higher production of IFN-γ, TNF-α, and perforin compared to the Ly6C- subsets. Overall, this study demonstrates the heterogeneity of virtual memory CD8 T cells and highlights the cytokine-dependent nature for their development.
Project description:Parasitic helminths induce the production of interleukin (IL)-4 which causes the expansion of virtual memory CD8+ T cells (TVM), a cell subset contributing to the control of viral coinfection. However, the mechanisms regulating IL-4-dependent TVM activation and expansion during worm infection remain ill defined. We used single-cell RNA sequencing of CD8+ T cells to investigate IL-4-dependent TVM responses upon helminth infection in mice. Gene signature analysis of CD8+ T cells identified a cell cluster marked by CD22, a canonical regulator of B cell activation, as a specific and selective surface marker of IL-4-induced TVM cells. CD22+ TVM were enriched for IFN-γ and granzyme A and retained a diverse TCR repertoire, while enriched in CDR3 sequences with features of self-reactivity. Deletion of CD22 expression in CD8+ T cells enhanced TVM responses to helminth infection, indicating that this inhibitory receptor modulates TVM responses. Thus, helminth-induced IL-4 drives the expansion and activation of self-reactive TVM in the periphery that is counter-inhibited by CD22
Project description:Virtual memory T (TVM) cells are a T-cell subtype that exhibit a memory phenotype without prior exposure to a foreign antigen. Although several recent studies suggest that TVM cells exert anti-viral and anti-bacterial function, pathological roles of TVM cells causing inflammatory diseases have not been studied. Here, we identified a novel CD8+ T-cell subset (CD44s-hiCD49dlo CD8+ T cells), which is originated from TVM cells and can cause a chronic inflammatory disease, alopecia areata (AA). In the skin of alopecic mice, we detected a distinct TVM-cell subpopulation characterized by superior expression of CD44 and features of tissue residency, which was transcriptionally, phenotypically, and functionally distinct from conventional CD8+ TVM cells. Mechanistically, this cell population could be induced from conventional TVM cells by IL-12, IL-15, and IL-18 stimulation. Moreover, the pathological activity of CD44s-hiCD49dlo CD8+ T cells was mediated by NKG2D-depedent innate-like cytotoxicity against target cells, which was further augmented by IL-15 stimulation and triggered the onset of disease. Collectively, our results suggest a new immunological mechanism through which TVM cells can cause chronic inflammatory disease by innate-like cytotoxicity.
Project description:Virtual memory T (TVM) cells are a T-cell subtype that exhibit a memory phenotype without prior exposure to a foreign antigen. Although several recent studies suggest that TVM cells exert anti-viral and anti-bacterial function, pathological roles of TVM cells causing inflammatory diseases have not been studied. Here, we identified a novel CD8+ T-cell subset (CD44s-hiCD49dlo CD8+ T cells), which is originated from TVM cells and can cause a chronic inflammatory disease, alopecia areata (AA). In the skin of alopecic mice, we detected a distinct TVM-cell subpopulation characterized by superior expression of CD44 and features of tissue residency, which was transcriptionally, phenotypically, and functionally distinct from conventional CD8+ TVM cells. Mechanistically, this cell population could be induced from conventional TVM cells by IL-12, IL-15, and IL-18 stimulation. Moreover, the pathological activity of CD44s-hiCD49dlo CD8+ T cells was mediated by NKG2D-depedent innate-like cytotoxicity against target cells, which was further augmented by IL-15 stimulation and triggered the onset of disease. Collectively, our results suggest a new immunological mechanism through which TVM cells can cause chronic inflammatory disease by innate-like cytotoxicity.
Project description:Effects of IL-4 on CD8 T cells functions are largely unknown. IL-4 induces survival and proliferation of CD8 T cells, but several studies suggest that IL-4 could also affect several functions of CD8 T cells such as cytotoxicity. Our team has shown that IL-4 repress the expression of Ccl5 in vitro. To define more precisely the impact of IL-4 on CD8 T cells, we performed a whole genome expression microarray analysis of naive and memory CD8 T cells cultured in presence or absence of IL-4. This approach allowed us to define the IL4-gene-expression signature on CD8 T cells. 18 samples were processed. Two populations of F5 naive CD8 T cells were FACS-sorted: samples from each population were incubated 20 hours with IL-7 in presence or absence of IL-4. Thus, a total of 6 “Naive” samples were processed. In addition, 4 populations of F5 TIM memory CD8 T cells were FACS-sorted: samples from 2 of these populations were incubated 20 hours in presence of IL-7 and/or IL-4, or in medium alone. Thus, 12 “Memory” samples were processed.
Project description:We found a unique subset of effector memory (EM) CD8+ T cells that expressed high levels of IL-6 receptor in human peripheral blood. These cells which also expressed high levels of IL-7Ra (referred to as IL-6R high IL-7Rahigh cells) had the a distinct gene expression profile and cellular characteristics compared to other EM CD8+ T cells. IL-6R high IL-7Ra high cells were early differentiated EM CD8+ T cells with decreased expression of T-bet, KLRG1, perforin and granzyme B. These cells had increased cell proliferation likely secondary to enhanced IL-2 production and high affinity IL-2R expression. IL-6R high IL-7Ra high EM CD8+ T cells exclusively produced high levels of IL-2, IL-5, IL-9 and IL-13 although IFN-r was produced by this cell subset and other EM CD8+ T cells. Of interest, IL-6R high IL-7Ra high EM CD8+ T cells expanded in the peripheral blood of patients with chronic obstructive pulmonary disease (COPD) and asthma where CD8+ T cells, IL-13 and IFN-r are suggested to be involved in the pathogenesis. Being the early-differentiated EM CD8+ T cells with a potent capacity to proliferate, survive and generate multiple cytokines, IL-6R high IL-7Ra high EM CD8+ T cells may serve as a primary reservoir for effector CD8+ T cells which potently expand and produce cytokines upon immune stimulation. Duplicate experiments were performed for each condition. In each condition, we independently prepared total RNA using the RNeasy mini kit (Qiagen) and assessed RNA integrity using Bioanalyzer 2100 (Agilent)- RINs were close to 10 for all samples. RNA was then amplified and hybridized to the Illumina HumanHT-12 v4.0 BeadChip, according to Illumina standard protocols.
Project description:A primary immune response is typically initiated in secondary lymphoid organs. Virtual memory CD8+ T (TVM) cells are antigen-inexperienced T cells of a central-memory phenotype, acquired through self antigen-driven homeostatic proliferation. Unexpectedly, here we find that, TVM cells are composed of CCR2+ and CCR2- subsets that differentially elaborate a spectrum of effector- and memory-poised functions directly in the tissue. During a primary flu infection, TVM cells rapidly infiltrate the lung in the first day and execute early viral control. TVM cells that recognize viral antigen are retained in the tissue, clonally expand independent of secondary lymphoid organs, and preferentially give rise to tissue-resident memory cells. By orchestrating an extra-lymphoid primary response, heterogenous TVM cells bridge innate reaction and adaptive memory directly in the infected tissue.