Biology subjects

Stein, J. V.

Publications and source records attributed to Stein, J. V..

8 recordsLinked to original sources

bioRxiv2024

A lymphoid tissue chemokine checkpoint prevents loss of CD8+ T cell functionality

The generation of effector CD8+ T cells (TEFF) requires activation of naive CD8+ T cells (TN) by dendritic cells (DCs) within lymphoid tissue. To date, it remains elusive how the duration of TN-DC interactions and integration of activation signals are controlled in vivo. Here, we report that lymphoid stroma-secreted ligands for CCR7 constrained interaction duration by gradually inducing CD8+ T cell release from DCs. At late time points of interactions, CCR7 ligands repositioned the F-actin-promoting factor DOCK2 away from the DC interface to enable CD8+ T cell detachment, proliferation onset and acquisition of cytotoxicity. Lack of CCR7 signaling, as during ex vivo activation or in chronically inflamed lymphoid tissue, caused sustained T cell-DC interactions, and generated dysfunctional TEFF with high expression of inhibitory receptors, impaired antimicrobial activity, and poor recall responses. In sum, our findings uncover that lymphoid stromal chemokines act as built-in "disruptors" of T cell-DC interactions for long-term preservation of TEFF functionality.

immunology↗

bioRxiv2024

Glia-Mediated Antigen Presentation In The Retina During Degeneration

Glia antigen-presenting cells (APCs) are pivotal regulators of immune surveillance within the retina, maintaining tissue homeostasis and promptly responding to insults. The intricate mechanisms underlying their local coordination and activation remain unclear. Our study integrates an animal model of retinal injury, retrospective analysis of human retinas, and in vitro experiments to elucidate insights into the pivotal role of antigen presentation in neuroimmunology during retinal degeneration, uncovering the involvement of various glial cells, notably Muller glia, and microglia. Glial cells act as sentinels, detecting antigens released during degeneration and interacting with T-cells via MHC molecules, which are essential for immune responses. Microglia function as APCs via the MHC class II pathway, upregulating key molecules such as Csf1r and cytokines. In contrast, Muller cells act as atypical APCs through the MHC class I pathway, exhibiting upregulated antigen processing genes and promoting a CD8+ T-cell response. Distinct cytokine signaling pathways, including TNF- and IFN, contribute to the immune balance. Human retinal specimens corroborate these findings, demonstrating glial activation and MHC expression correlating with degenerative changes. In vitro assays also confirmed differential T-cell migration responses to activated microglia and Muller cells, highlighting their role in shaping the immune milieu within the retina. These insights emphasize the complex interplay between glial cells and T-cells, influencing the inflammatory environment and potentially modulating degenerative processes. In summary, our study emphasizes the involvement of retinal glial cells in modulating the immune response after insults to the retinal parenchyma. Thus, unraveling the intricacies of glia-mediated antigen presentation in retinal degeneration is essential for developing precise therapeutic interventions for retinal pathologies.

neuroscience↗

bioRxiv2023

MACROPHAGES COORDINATE IMMUNE RESPONSE TO LASER-INDUCED INJURY VIA EXTRACELLULAR TRAPS

Macrophages/monocytes, the primary contributors to chronic inflammation in degenerated retinas, orchestrate intricate immune responses. They remain enigmatic in their local coordination and activation mechanisms. Innovations in experimental systems enable real-time exploration of immune cell interactions and temporal dimensions in response. In preclinical mouse models, we use in vivo microscopy to unravel how macrophages/monocytes govern microglia and PL responses spatio-temporally. Our findings underscore the pivotal role of innate immune cells, especially macrophages/monocytes, in regulating retinal repair. The absence of neutrophil and macrophage infiltration aids parenchymal integrity restoration, while their depletion, particularly macrophages/monocytes, impedes vascular recovery. Innate immune cells, when activated, release chromatin and granular proteins, forming extracellular traps (ETs), critical for tissue repair by modulating neutrophil and T-cell responses. Our investigations demonstrate that pharmacological inhibition of ETosis with Cl-amidine enhances retinal and vascular repair, surpassing the effects of blocking innate immune cell recruitment. Simultaneously, Cl-amidine treatment reshapes the inflammatory response, causing neutrophils, helper, and cytotoxic T-cells to cluster primarily in the superficial capillary plexus, affecting retinal microvasculature perfusion. Our data offer novel insights into innate immunitys role in responding to retinal damage, potentially informing more effective immunotherapeutic strategies for neurodegenerative diseases.

neuroscience↗

bioRxiv2021

B cell-intrinsic requirement for WNK1 kinase in T cell-dependent antibody responses

Migration and adhesion play critical roles in B cells, regulating recirculation between lymphoid organs, migration within lymphoid tissue and interaction with CD4+ T cells. However, there is limited knowledge of how B cells integrate chemokine receptor and integrin signaling with B cell activation to generate efficient humoral responses. Here we show that the WNK1 kinase, a regulator of migration and adhesion, is essential in B cells for T-dependent antibody responses. We demonstrate that WNK1 transduces signals from the BCR, CXCR5 and CD40, and using intravital imaging we show that WNK1 regulates migration of naive and activated B cells, and their interactions with T cells. Unexpectedly, we show that WNK1 is required for BCR- and CD40-induced proliferation, acting through the OXSR1 and STK39 kinases, and for efficient B cell-T cell collaboration in vivo. Thus, WNK1 is critical for humoral immune responses, by regulating B cell migration, adhesion and T cell-dependent activation. SummaryThe WNK1 kinase is essential in B cells for T-dependent antibody responses because it is activated by signaling from BCR, CXCR5 and CD40 and regulates B cell migration, adhesion, T-dependent activation, and differentiation into germinal center B cells and plasma cells.

immunology↗

bioRxiv2021

Multi-tier mechanics control stromal adaptations in swelling lymph nodes

Lymph nodes (LNs) comprise two main structural elements: Fibroblastic reticular cells (FRCs) that form dedicated niches for immune cell interaction and capsular fibroblasts that build a shell around the organ. While LNs are fairly stable in size during homeostatic conditions, immunological challenge causes more than 10-fold increase in size within only a few days. How a solid organ can accommodate such extreme volumetric changes is poorly understood. Here, we characterize the biomechanics of LN swelling on the cellular and organ scale. We identify lymphocyte trapping by influx and proliferation as drivers of an outward pressure force, causing FRCs and their associated conduits to stretch. After an initial phase of relaxation, FRCs sense the resulting strain via cell matrix adhesions, which coordinates local growth and remodeling of the stromal network. While the expanded FRC network adopts its typical configuration, a massive fibrotic reaction of the organ capsule sets in and counters further organ expansion. Thus, different fibroblast populations mechanically control LN swelling in a multi-tier fashion.

immunology↗

bioRxiv2020

CD8+ T cell priming in oral mucosa-draining lymph nodes supports systemic immunity

The gastrointestinal (GI) tract constitutes an essential barrier against ingested pathogens. While immune reactions are well-studied in the lower GI tract, it remains unclear how adaptive immune responses are initiated during microbial challenge of the oral mucosa, the primary site of pathogen encounter in the upper GI tract. Here, we identify mandibular lymph nodes (mandLN) as sentinel lymphoid organs that collect orally administered Listeria monocytogenes (Lm), leading to local CD8+ T cell activation. In contrast to CD8+ T effector cells (TEFF) generated in mesenteric lymph nodes, mandLN CD8+ TEFF lacked a gut-seeking phenotype but contributed to systemic host protection. Accordingly, mandLN stromal and dendritic cells expressed low levels of enzymes required for gut homing imprinting. Our findings extend the concept of regional specialization of immune responses along the length of the GI tract, with mandLN acting as oral lymph-draining counterparts of intestinal lymph-draining LN of the lower GI tract. SummaryListeria monocytogenes ingestion leads to priming of cytotoxic T cells in oral mucosa draining mandibular lymph nodes, which contribute to systemic host protection.

immunology↗

bioRxiv2020

Dendritic cell actin dynamics controls T cell priming efficiency at the immunological synapse

Dendritic cells (DCs) are crucial for the priming of naive T cells and the initiation of adaptive immunity. Priming is initiated at a heterologous cell-cell contact, the immunological synapse (IS). While it is established that actin dynamics regulates signalling at the T cell side of the contact, little is known about the cytoskeletal contribution on the DC side. We show that that the DC cytoskeleton is decisive for the formation of a multifocal synaptic structure, which correlates with T cell priming efficiency. We demonstrate that DC actin appears in transient foci at the IS and that these foci are dynamized by the WAVE complex. Absence of WAVE in DCs leads to stabilized contacts with T cells, caused by an increase in ICAM1-integrin mediated cell-cell adhesions. This results in a lower number of activated and proliferating T cells. Our results reveal an important role of DC actin in the regulation of synaptic contacts with crucial relevance for full T cell expansion.

cell biology↗

bioRxiv2019

3D imaging of undissected optically cleared Anopheles stephensi mosquitoes infected with Plasmodium parasites

Malaria is a life-threatening disease, caused by Apicomplexan parasites of the Plasmodium genus. The Anopheles mosquito is necessary for the sexual replication of these parasites and for their transmission to vertebrate hosts, including humans. Imaging of the parasite within the insect vector has been attempted using multiple microscopy methods, most of which are hampered by the presence of the light scattering opaque cuticle of the mosquito. So far, imaging of the Plasmodium mosquito stages depended on either sectioning or surgical dissection of important anatomical sites, such as the midgut and the salivary glands. Optical projection tomography (OPT) and light sheet fluorescence microscopy (LSFM) enable imaging fields of view in the centimeter scale whilst providing micrometer resolution. In this paper, we present reconstructions of the whole body of Plasmodium-infected, optically cleared Anopheles stephensi mosquitoes and their midguts. The 3D-reconstructions from OPT imaging show detailed features of the mosquito anatomy and enable overall localization of parasites in midguts. Additionally, LSFM imaging of mosquito midguts shows detailed distribution of oocysts in extracted midguts.

microbiology↗