CD8 + T cells are specialized cells of the adaptive immune system capable of finding and eliminating pathogen-infected cells. To date it has not been possible to observe the destruction of any pathogen by CD8 + T cells in vivo. Here we demonstrate a technique for imaging the killing of liver-stage malaria parasites by CD8 + T cells bearing a transgenic T cell receptor specific for a parasite epitope. We report several features that have not been described by in vitro analysis of the process, chiefly the formation of large clusters of effector CD8 + T cells around infected hepatocytes. The formation of clusters requires antigen-specific CD8 + T cells and signaling by G protein-coupled receptors, although CD8 + T cells of unrelated specificity are also recruited to clusters. By combining mathematical modeling and data analysis, we suggest that formation of clusters is mainly driven by enhanced recruitment of T cells into larger clusters. We further show various death phenotypes of the parasite, which typically follow prolonged interactions between infected hepatocytes and CD8 + T cells. These findings stress the need for intravital imaging for dissecting the fine mechanisms of pathogen recognition and killing by CD8 + T cells.Plasmodium | immunity | lymphocytes
Malarial infection is initiated when the sporozoite form of the Plasmodium parasite is inoculated into the skin by a mosquito. Sporozoites invade hepatocytes in the liver and develop into the erythrocyte-infecting form of the parasite, the cause of clinical blood infection. Protection against parasite development in the liver can be induced by injection of live attenuated parasites that do not develop in the liver and thus do not cause blood infection. Radiation-attenuated sporozoites (RAS) and genetically attenuated parasites are now considered as lead candidates for vaccination of humans against malaria. Although the skin appears as the preferable administration route, most studies in rodents, which have served as model systems, have been performed after i.v. injection of attenuated sporozoites. In this study, we analyzed the early response to Plasmodium berghei RAS or wild-type sporozoites (WTS) injected intradermally into C57BL/6 mice. We show that RAS have a similar in vivo distribution to WTS and that both induce a similar inflammatory response consisting of a biphasic recruitment of polymorphonuclear neutrophils and inflammatory monocytes in the skin injection site and proximal draining lymph node (dLN). Both WTS and RAS associate with neutrophils and resident myeloid cells in the skin and the dLN, transform inside CD11b+ cells, and induce a Th1 cytokine profile in the dLN. WTS and RAS are also similarly capable of priming parasite-specific CD8+ T cells. These studies delineate the early and local response to sporozoite injection into the skin, and suggest that WTS and RAS prime the host immune system in a similar fashion.
Malaria infection begins when the sporozoite stage of Plasmodium is inoculated into the skin of a mammalian host through a mosquito bite. The highly motile parasite not only reaches the liver to invade hepatocytes and transform into erythrocyte-infective form. It also migrates into the skin and to the proximal lymph node draining the injection site, where it can be recognized and degraded by resident and/or recruited myeloid cells. Intravital imaging reported the early recruitment of brightly fluorescent Lys-GFP positive leukocytes in the skin and the interactions between sporozoites and CD11c + cells in the draining lymph node. We present here an efficient procedure to recover, identify and enumerate the myeloid cell subsets that are recruited to the mouse skin and draining lymph node following intradermal injection of immunizing doses of sporozoites in a murine model. Phenotypic characterization using multi-parametric flow cytometry provides a reliable assay to assess early dynamic cellular changes during inflammatory response to Plasmodium infection. Video LinkThe video component of this article can be found at
Introduction-Previous work has shown that the vaginal microbiome decreases in Lactobacilluspredominance and becomes more diverse following menopause. It has also been shown that estrogen therapy restores Lactobacillus-dominance in the vagina, and that topical estrogen is associated with OAB symptom improvement. We now know that the bladder contains a unique microbiome, and increased bladder microbiome diversity is associated with OAB. However, there is no understanding of how quickly each pelvic floor microbiome responds to estrogen or if those changes are associated with symptom improvement.Study Design-Analysis of data from post-menopausal participants in two trials (NCT02524769 and NCT02835846) who chose vaginal estrogen as their primary OAB treatment and used 0.5 grams of conjugated estrogen (Premarin Cream, (Pfizer, New York City, NY)) twice weekly for 12 weeks. Baseline and 12-week follow-up data included the OAB-q questionnaire and participants provided catheterized urine, vaginal swabs, perineal swabs, and voided urine. Microbes were detected by an enhanced culture protocol. Linear mixed models were used to estimate microbiome changes over time. Urinary AMP activity was assessed by a bacterial growth inhibition assay and correlated with relative abundance of members of the urobiome.Results-Twelve weeks of estrogen treatment resulted in decreased microbial diversity within the vagina (Shannon, p=0.047; Richness, p=0.043), but not in the other niches. A significant increase in Lactobacillus was detected in the bladder (p=0.037), but not the vagina (p=0.33), perineum (p=0.56), or voided urine (p=0.28). The change in Lactobacillus levels in the bladder was associated with modest changes in urgency incontinence symptoms (p=0.02). The relative abundance of the genus Corynebacterium correlated positively with urinary AMP activity after estrogen treatment. Conclusion-Estrogentherapy may change the microbiome of different pelvic floor niches. The vagina begins to decrease in diversity and the bladder experiences a significant increase in Lactobacillus levels; the latter is correlated with a modest improvement in the symptom severity sub-scale of the OAB-q. CondensationEstrogen therapy for overactive bladder resulted in decreased bladder bacterial diversity and increased bladder Lactobacillus, which were associated with modest changes in urgency incontinence symptoms.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.