Project description:Purpose: The intestine's main function is to digest and absorb dietary nutrients, with help from the absorptive epithelium and underlying vasculature and lymphatic system, as well as the microbiome. The intestine also houses the largest immune cell population in the body, tasked with providing resistance to toxins and invading pathogens while maintaining tolerance to dietary and microbial antigens, either by local action or lymphatic trafficking to the gut-draining lymph nodes (gLNs) to mount adaptive responses. While previous studies revealed the drainage map to various gLNs along the murine gut, and described immunological differences between gLNs, the underlying cellular components and the functional consequences of gut segment-specific drainage have not been systematically addressed. We sought to understand how compartmentalized lymphatic drainage of the intestinal milieu contributes to immune responses towards luminal antigens. Results: Here we report that gLNs are immunologically unique according to the functional gut segment they drain. Stromal and dendritic cell gene signatures, as well as adaptive T cell polarization against the same luminal antigen, differed between gLNs along the intestine, the proximal small intestine–draining gLNs preferentially giving rise to tolerogenic and the distal gLNs to pro-inflammatory T cell responses. This compartmentalized dichotomy could be perturbed by duodenal infection, surgical removal of select distal gLNs, dysbiosis, or ectopic antigen delivery, impacting both lymphoid organ and tissue immune responses. Conclusions: Our findings reveal that the conflict between tolerogenic and inflammatory adaptive responses is in part resolved by discrete gLN drainage, and encourage gut segment-specific antigen targeting for therapeutic immune modulation.
Project description:Lymph nodes are secondary lymphoid tissues that play a critical role in filtering the lymph and supporting adaptive immune responses. Surgical resection of LNs, radiation therapy or infections may damage lymphatic vasculature and compromised immune functions. Here, we describe the generation of functional synthetic lympho-organoids (LOs) using LN stromal progenitors and decellularized extra cellular matrix-based scaffolds. We show that upon transplantation at the site of resected LNs, LOs become integrated into the endogenous lymphatic vasculature and efficiently restore lymphatic drainage and perfusion. Upon immunization, LOs support the activation of antigen-specific immune responses, thus acquiring properties of native lymphoid tissues. These findings provide the first proof-of-concept for the development of synthetic lympho-organoids suitable to restore lymphatic and immune cell functions.
Project description:Despite the success of currently authorized vaccines for the reduction of severe COVID-19 disease risk, rapidly emerging viral variants continue to drive pandemic waves of infection, resulting in numerous global public health challenges. Progress will depend on future advances in prophylactic vaccine activity, including advancement of candidates capable of generating more potent induction of cross-reactive T cells and durable cross-reactive antibody responses. Here we evaluated an Amphiphile (AMP) adjuvant, AMP-CpG, admixed with SARS-CoV-2 Spike receptor binding domain (RBD) immunogen, as a lymph node-targeted protein subunit vaccine (ELI-005) in mice and non-human primates (NHPs). AMP-mediated targeting of CpG DNA to draining lymph nodes resulted in comprehensive local immune activation characterized by extensive transcriptional reprogramming, inflammatory proteomic milieu, and activation of innate immune cells as key orchestrators of antigen-directed adaptive immunity. Prime-boost immunization with AMP-CpG in mice induced potent and durable T cell responses in multiple anatomical sites critical for prophylactic efficacy and prevention of severe disease. Long-lived memory responses were rapidly expanded upon re-exposure to antigen. In parallel, RBD-specific antibodies were long-lived, and exhibited cross-reactive recognition of variant RBD. AMP-CpG-adjuvanted prime-boost immunization in NHPs was safe and well tolerated, while promoting multi-cytokine-producing circulating T cell responses cross-reactive across variants of concern (VOC). Expansion of RBD-specific germinal center (GC) B cells in lymph nodes correlated to rapid seroconversion with variant-specific neutralizing antibody responses exceeding those measured in convalescent human plasma. These results demonstrate the promise of lymph-node adjuvant-targeting to coordinate innate immunity and generate robust adaptive responses critical for vaccine efficacy.
Project description:Fibroblastic reticular cells (FRC) shape the organization of secondary lymphoid organs and actively promote the induction of immune responses by coordinating the interaction of innate and adaptive immune cells. However, the mechanisms underlying FRC functions during viral infections have remained largely unexplored. In the study, we combined FRC-specific genetic ablation of the type 1 IFN-alpha receptor (IFNAR) with high-dimensional transcriptomics analyses to elaborate the phenotypical alterations and functional consequences of impaired innate immunological sensing in FRC during lymph node-restricted viral infection
Project description:Activation of the innate immune system via pattern recognition receptors (PRRs) is key to generate lasting adaptive immunity. PRRs detect unique chemical patterns associated with invading microorganism, but if and how the physical properties of PRR ligands influence development of the immune response remains unknown. Through the study of fungal mannans we show that the physical form of PRR ligands dictates the immune response. Soluble mannans are immunosilent in the periphery but elicit a potent pro-inflammatory response in the draining lymph node (dLN). By modulating the physical form of mannans, we developed a formulation that targets both the periphery and dLN. When combined with viral glycoprotein antigens, this mannan formulation broadens epitope recognition, elicits potent antigen-specific neutralizing antibodies, and confers protection against viral infections of the lung. Thus, the physical properties of microbial ligands determine the outcome of the immune response and can be harnessed for vaccine development.
Project description:Induction of adaptive immune responses to commensal microbes is critical for intestinal homeostasis, and perturbation of these responses is associated with multiple chronic inflammatory disorders. However, the mechanisms underlying the induction and regulation of mucosal B cells targeting commensal microbes remain poorly understood, in part due to a lack of tools to identify commensal-specific B cells ex vivo. To address this, we first sought to identify immunodominant protein epitopes recognized by Segmented Filamentous Bacteria (SFB) specific serum antibodies using a whole-genome phage display screen and identified immunogenic proteins engaging IgA, IgG1 and IgG2b responses. Using these antigens, we generated B cell tetramers to identify and track SFB-specific B cell responses in the gut associated lymphoid tissue during natural and de novo colonization. We identified a compartmentalized response in B cell activation between Peyer’s patches and mesenteric lymph nodes, with a gradient of IgA, IgG1 and IgG2b isotypes along the small intestine, and selective production of IgG2b with the mesenteric lymph node chain. VDJ sequencing analyses and generation of SFB-specific monoclonal antibodies identified that somatic hypermutation drives affinity maturation to SFB derived antigens under homeostatic conditions. By combining phage display screening and B cell tetramer technologies, we now enable antigen-level based studies of immunity to intestinal microbes, which will advance our understanding of the ontogeny and function of commensal-specific B cell responses in tissue immunity, inflammation and repair.
Project description:Despite the success of currently authorized vaccines for the reduction of severe COVID-19 disease risk, rapidly emerging viral variants continue to drive pandemic waves of infection, resulting in numerous global public health challenges. Progress will depend on future advances in prophylactic vaccine activity, including advancement of candidates capable of generating more potent induction of cross-reactive T cells and durable cross-reactive antibody responses. Here we evaluated an Amphiphile (AMP) adjuvant, AMP-CpG, admixed with SARS-CoV-2 Spike receptor binding domain (RBD) immunogen, as a lymph node-targeted protein subunit vaccine (ELI-005) in mice and non-human primates (NHPs). AMP-mediated targeting of CpG DNA to draining lymph nodes resulted in comprehensive local immune activation characterized by extensive transcriptional reprogramming, inflammatory proteomic milieu, and activation of innate immune cells as key orchestrators of antigen-directed adaptive immunity. Prime-boost immunization with AMP-CpG in mice induced potent and durable T cell responses in multiple anatomical sites critical for prophylactic efficacy and prevention of severe disease. Long-lived memory responses were rapidly expanded upon re-exposure to antigen. In parallel, RBD-specific antibodies were long-lived, and exhibited cross-reactive recognition of variant RBD. AMP-CpG-adjuvanted prime-boost immunization in NHPs was safe and well tolerated, while promoting multi-cytokine-producing circulating T cell responses cross-reactive across variants of concern (VOC). Expansion of RBD-specific germinal center (GC) B cells in lymph nodes correlated to rapid seroconversion with variant-specific neutralizing antibody responses exceeding those measured in convalescent human plasma. These results demonstrate the promise of lymph-node adjuvant-targeting to coordinate innate immunity and generate robust adaptive responses critical for vaccine efficacy.
Project description:Lymph nodes (LNs) serve as hubs for the interaction and communication between tissue-derived and blood-derived immune cells. Here we analyzed mouse lymph node (LN) lymphatic endothelial cells (LEC) at single cell resolution. Clustering identifies five well-delineated subsets, including two medullary sinus subsets not recognized previously as distinct. Nearest neighbor alignments in trajectory space position the major subsets in a sequence that recapitulates known and suggests novel features of LN lymphatic organization, providing a transcriptional map of the lymphatic endothelial niches and of the transitions between them. Differences in gene expression reveal specialized programs for (1) subcapsular ceiling endothelial interactions with the capsule connective tissue and cells, (2) subcapsular floor regulation of lymph borne cell entry into the LN parenchyma and antigen presentation, and (3) medullary subset specialization for pathogen interactions and LN remodeling. LEC of the subcapsular sinus floor and medulla, which represent major sites of cell entry and exit from the LN parenchyma respectively, respond robustly to oxazolone inflammation challenge with enriched signaling pathways that converge on both innate and adaptive immune responses.
Project description:Lymph nodes (LNs) serve as hubs for the interaction and communication between tissue-derived and blood-derived immune cells. Here we analyzed mouse lymph node (LN) lymphatic endothelial cells (LEC) at single cell resolution. Clustering identifies five well-delineated subsets, including two medullary sinus subsets not recognized previously as distinct. Nearest neighbor alignments in trajectory space position the major subsets in a sequence that recapitulates known and suggests novel features of LN lymphatic organization, providing a transcriptional map of the lymphatic endothelial niches and of the transitions between them. Differences in gene expression reveal specialized programs for (1) subcapsular ceiling endothelial interactions with the capsule connective tissue and cells, (2) subcapsular floor regulation of lymph borne cell entry into the LN parenchyma and antigen presentation, and (3) medullary subset specialization for pathogen interactions and LN remodeling. LEC of the subcapsular sinus floor and medulla, which represent major sites of cell entry and exit from the LN parenchyma respectively, respond robustly to oxazolone inflammation challenge with enriched signaling pathways that converge on both innate and adaptive immune responses.