ScRNA-seq of mouse Plasmodium-specific TCR-transgenic CD4+ T cells prior to and after re-infection.
Ontology highlight
ABSTRACT: Naturally-acquired immunity to blood-stage malaria is associated with several effector CD4 + T subsets including germinal centre (GC) Tfh, Th1 and Tr1 cells. Children in malaria-endemic regions can experience repeated Plasmodium infections over short periods of time; yet the effect of reinfection on multiple co-existing effector and memory subsets remains unclear. Here, we tracked antigen-experienced TCR-transgenic CD4+ T cells during Plasmodium re-infection in mice using scRNA-seq.
Project description:Naturally-acquired immunity to blood-stage malaria is associated with several effector CD4 + T subsets including germinal centre (GC) Tfh, Th1 and Tr1 cells. Children in malaria-endemic regions can experience repeated Plasmodium infections over short periods of time; yet the effect of reinfection on multiple co-existing effector and memory subsets remains unclear. Here, we tracked antigen-experienced polyclonal CD4+ T cells during Plasmodium re-infection in mice using scRNA-seq/TCR-seq.
Project description:Naturally-acquired immunity to blood-stage malaria is associated with several effector CD4 + T subsets including germinal centre (GC) Tfh, Th1 and Tr1 cells. Here, we mapped the locations of effector CD4+ T cell subsets during post-Plasmodium convalescence using Slide-seqV2.
Project description:Controlled human malaria infection is a powerful experimental medicine tool to understand the human immune response to a first ever malaria infection. Here we have taken this approach a step further and conducted the first human malaria reinfection trial in the modern era. Volunteers were challenged up to three times with Plasmodium falciparum in 4- to 8-month intervals. Remarkably, parasite densities and the dynamics of blood-stage infection were not altered over the course of three homologous infections. Using whole blood RNA-sequencing we tracked the host immune response through time and found that the emergency myeloid response, which triggers systemic inflammation and the global recruitment of T cells into lymphoid tissues, is not altered by repeated infection. Six days after parasite clearance, when the innate response subsides, T cells return to the circulation and reflect the outcome of critical cell-cell interactions within the inflamed spleen. By transcriptionally profiling flow sorted CD4+ T cell subsets after their release from the tissue we could show that TH1 polarised effector response in naïve hosts is tolerised upon re-challenge to avoid collateral tissue damage. Instead, a subset of specialised cytokine-producing CD4+ T cells are activated to promote essential protective immune functions. Together these data indicate that innate and adaptive immune responses can be uncoupled in malaria and illustrate that human hosts prioritises damage limitation (tolerance) over parasite clearance (resistance) to quickly acquire clinical immunity.
Project description:Blood-stage malaria infection induces differentiation of several effector CD4 + T subsets including Tfh and Th1 cells. The cues and microarchitectural niches required in secondary lymphoid organs for their formation were previously uncharacterised. Here we used scRNA-seq to profile splenocyte transcriptomes at steady state or upon malaria infection as a reference dataset for deconvolution of spatial transcriptomic data.
Project description:CD4+ T cells are critical for defense against the Plasmodium parasites that cause malaria. To better understand CD4+ T cell effector mechanisms during malaria, we performed microarray analysis of CD4+ T cells from naïve and infected mice. Comparison of activated (CD44 hi CD62L lo) CD4+ T cells from infected mice to bulk CD4+ T cells from naïve mice revealed a subset of genes that were upregulated by infection with Plasmodium chabaudi. These results help generate a more complete picture of CD4+ T cell function in malaria.
Project description:Plasmodium falciparum (Pf) malaria causes high rates of morbidity and mortality and lacks an effective vaccine. Clinical immunity develops in residents of malaria endemic regions which confers reduced clinical symptoms during infection and protects against severe disease. We hypothesized that understanding the immune mechanisms of clinical immunity could inform vaccine design to improve efficacy. We compared the peripheral blood cellular and humoral immune responses during Pf malaria infection between clinically susceptible and protected participants from a malaria endemic region in Malawi during a prospective 18-month longitudinal study. Participant classifications were defined by the number of recurrent clinical malaria episodes with susceptible participants having more than three while protected less than one episode during the study period. Protected participants exhibited higher immunoglobulin G (IgG) breadth and titers against Pf antigens, and greater antibody (Ab)-dependent Pf opsonization compared to susceptible participants, consistent with our classifications. Using high dimensional mass cytometry (CyTOF) and spectral flow cytometry, and single-cell transcriptomic analyses, we identified expanded memory CD4+ T cell clonotypes in the blood of protected participants undergoing malaria infection. These cells express a strong cytolytic T helper 1 effector program with transcripts encoding granzymes (A, B, H, M), granulysin, NKG7 and the ZEB2 master transcriptional regulator of terminally differentiated effector T cells. ZEB2+ memory CD4+ T cells were CD39hiTIGIThi and expressed multiple chemotactic and inhibitory receptors. Yet, their levels of several chemokine and checkpoint inhibitory receptors were reduced in protected compared to susceptible individuals. We propose that clonally expanded ZEB2+ cytolytic memory CD4+ Th1 cells could represent essential contributors to clinical immunity against Pf malaria infection.
Project description:Malaria infection elicits both protective and pathogenic immune responses, and IL-27 is a critical cytokine that regulate effector responses during infection. Here, we identified a critical window of CD4+ T cell responses that is targeted by IL-27. Neutralization of IL-27 during acute infection with Plasmodium chabaudi expanded specific CD4+ T cells, which were maintained at high levels thereafter. In the chronic phase, Plasmodium-specific CD4+ T cells in IL-27-neutralized mice consisted mainly of CD127+KLRG1- and CD127-KLRG1+ subpopulations that displayed distinct cytokine production, proliferative capacity and are maintained in a manner independent of active infection. Single cell RNA-seq analysis revealed that these CD4+ T cell subsets formed independent clusters that express unique Th1-type genes. These IL-27-neutralized mice exhibited enhanced cellular and humoral immune responses and protection. These findings demonstrate that IL-27, which is produced during the acute phase of malaria infection, inhibits the development of unique Th1 memory precursor CD4+ T cells, suggesting potential implications for the development of vaccines and other strategic interventions.
Project description:T-dependent germinal center (GC) output, comprising plasma cells (PC) and memory B cells (MBC), is crucial for the clearance of Plasmodium infection and protection against reinfection. In this study, we examined the effect of an agonistic antibody targeting 4-1BB (CD137), a member of the Tumor Necrosis Factor Receptor Superfamily (TNFRSF), during experimental malaria. We found that exogenous 4-1BB stimulation dramatically enhanced humoral immune memory and protection from reinfection, despite delaying the effector GC response. Although fewer in number, single cell RNA and ATAC sequencing of MBCs from mice that received 4-1BB stimulation revealed clusters with a transcriptional and epigenetic signature indicative of superior recall and proliferative potential. Importantly, our results indicate that these effects are independent of parasite load or the inflammatory milieu but are dependent on IL-9R signaling in B cells. Our study proposes an immunomodulatory approach to enhance the quality of the MBC pool, providing superior protection during infection and vaccination, particularly in the context of malaria.
Project description:T-dependent germinal center (GC) output, comprising plasma cells (PC) and memory B cells (MBC), is crucial for the clearance of Plasmodium infection and protection against reinfection. In this study, we examined the effect of an agonistic antibody targeting 4-1BB (CD137), a member of the Tumor Necrosis Factor Receptor Superfamily (TNFRSF), during experimental malaria. We found that exogenous 4-1BB stimulation dramatically enhanced humoral immune memory and protection from reinfection, despite delaying the effector GC response. Although fewer in number, single cell RNA and ATAC sequencing of MBCs from mice that received 4-1BB stimulation revealed clusters with a transcriptional and epigenetic signature indicative of superior recall and proliferative potential. Importantly, our results indicate that these effects are independent of parasite load or the inflammatory milieu but are dependent on IL-9R signaling in B cells. Our study proposes an immunomodulatory approach to enhance the quality of the MBC pool, providing superior protection during infection and vaccination, particularly in the context of malaria.
Project description:This study was designed to determine the differences in gene transcripts between CD4+ T helper (Th)1, Tr1, and Tneg cells during controlled human malaria infection.