Biology subjects

Lund, A. W.

Publications and source records attributed to Lund, A. W..

7 recordsLinked to original sources

bioRxiv2023

Lymphatic vessel transit seeds precursors to cytotoxic resident memory T cells in skin draining lymph nodes

Resident memory T cells (TRM) provide rapid, localized protection in peripheral tissues to pathogens and cancer. While TRM are also found in lymph nodes (LN), how they develop during primary infection and their functional significance remains largely unknown. Here, we track the anatomical distribution of anti-viral CD8+ T cells as they simultaneously seed skin and LN TRM using a model of skin infection with restricted antigen distribution. We find exquisite localization of LN TRM to the draining LN of infected skin. LN TRM formation depends on lymphatic transport and specifically egress of effector CD8+ T cells that appear poised for residence as early as 12 days post infection. Effector CD8+ T cell transit through skin is necessary and sufficient to populate LN TRM in draining LNs, a process reinforced by antigen encounter in skin. Importantly, we demonstrate that LN TRM are sufficient to provide protection against pathogenic rechallenge. These data support a model whereby a subset of tissue infiltrating CD8+ T cells egress during viral clearance, and establish regional protection in the draining lymphatic basin as a mechanism to prevent pathogen spread. One Sentence SummaryT cell egress out of virally infected skin via afferent lymphatic vessels seeds CD8+ resident memory T cells in the draining lymph node.

immunology↗

bioRxiv2023

CXCR6 promotes dermal CD8+ T cell survival and transition to long-term tissue residence

Tissue resident memory T cells (TRM) provide protection against local re-infection, and yet the interstitial signals necessary for their formation and persistence remain incompletely understood. Here we show that antigen-dependent induction of the chemokine receptor, CXCR6, is a conserved adaptation to peripheral tissue infiltration that promotes TRM formation after viral infection. Deficient TRM formation in the absence of CXCR6 was not explained by canonical trafficking as CXCR6 was not required for tissue entry, was dispensable for the early accumulation of antigen-specific CD8+ T cells in skin, and did not restrain their exit. Further, single cell sequencing indicated that Cxcr6-/- CD8+ T cells were competent to acquire a transcriptional program of residence and TRM that formed were equally functional compared to their WT counterparts when reactivated greater than 100 days post primary infection. The reduced numbers observed at memory time points, where instead found to associate with impaired redox homeostasis and antioxidant capacity during the transition from effector to memory states. As such, Cxcr6-/- CD8+ T cells exhibited increased rates of apoptosis in the dermis relative to controls, which led to reduced numbers of TRM in the epidermis at memory. CXCR6 therefore promotes the metabolic adaptation of T cells as they engage antigen in tissue to increase the probability of memory differentiation and long-term residence. One Sentence SummaryCXCR6 promotes mechanisms of cellular adaptation to tissue that support local survival and the transition to tissue residence.

immunology↗

bioRxiv2022

T cell Egress via Lymphatic Vessels Limits the Intratumoral T cell Repertoire in Melanoma

Antigen-specific CD8+ T cell accumulation in tumors is a prerequisite for effective immunotherapy, and yet, the mechanisms of lymphocyte transit remain poorly defined. We find that tumor-associated lymphatic vessels control T cell exit from tumors via the chemokine CXCL12, and intratumoral antigen encounter tunes CXCR4 expression on effector CD8+ T cells. Only high affinity antigen downregulates CXCR4 and upregulates the CXCL12 decoy receptor, ACKR3, thereby reducing CXCL12 sensitivity and promoting T cell retention. A diverse repertoire of functional tumor-specific CD8+ T cells exit the tumor, thereby limiting tumor control. CXCR4 inhibition and loss of lymphatic-specific CXCL12 boosts T cell retention and enhances response to therapeutic immune checkpoint blockade. Strategies that limit T cell egress, therefore, provide a new tool to boost immunotherapy response. One-Sentence SummaryLymphatic vessel-mediated, antigen-dependent CD8+ T cell egress limits T cell accumulation in melanomas and impairs anti-tumor immunity.

immunology↗

bioRxiv2022

Single-Cell RNA Sequencing Reveals the Effects of Chemotherapy on Human Pancreatic Adenocarcinoma and its Tumor Microenvironment

The tumor microenvironment (TME) in pancreatic ductal adenocarcinoma (PDAC) is a complex ecosystem that drives tumor progression; however, in-depth single cell characterization of the PDAC TME and its role in response to therapy is lacking. We performed single-cell RNA sequencing on freshly collected human PDAC samples either before or after chemotherapy. Overall, we found a heterogeneous mixture of basal and classical cancer cell subtypes, along with distinct cancer-associated fibroblast and macrophage subpopulations. Strikingly, classical and basal-like cancer cells exhibited similar transcriptional responses to chemotherapy, and did not demonstrate a shift towards a basal-like transcriptional program among treated samples. We observed decreased ligand-receptor interactions in treated samples, particularly TIGIT on CD8+ T cells and its receptor on cancer cells, and identified TIGIT as the major inhibitory checkpoint molecule of CD8+ T cells. Our results suggest that chemotherapy profoundly impacts the PDAC TME and may promote resistance to immunotherapy.

cancer biology↗

bioRxiv2021

Quantitative multiplex immunohistochemistry reveals inter- and intra-patient lymphovascular and immune heterogeneity in primary cutaneous melanoma

PurposeQuantitative, multiplexed imaging is revealing complex spatial relationships between phenotypically diverse tumor infiltrating leukocyte populations and their prognostic implications. The underlying mechanisms and tissue structures that determine leukocyte distribution within and around tumor nests, however, remain poorly understood. While presumed players in metastatic dissemination, new preclinical data demonstrates that blood and lymphatic vessels (lymphovasculature) also dictate leukocyte trafficking within tumor microenvironments and thereby impact anti-tumor immunity. Here we interrogate these relationships in primary human cutaneous melanoma. Experimental DesignWe established a quantitative, multiplexed imaging platform to simultaneously detect immune infiltrates and tumor-associated vessels in formalin-fixed paraffin embedded patient samples. We performed a discovery, retrospective analysis of 28 treatment-naive, primary cutaneous melanomas. ResultsHere we find that the lymphvasculature and immune infiltrate is heterogenous across patients in treatment naive, primary melanoma. We categorized five lymphovascular subtypes that differ by functionality and morphology and mapped their localization in and around primary tumors. Interestingly, the localization of specific vessel subtypes, but not overall vessel density, significantly associated with the presence of lymphoid aggregates, regional progression, and intratumoral T cell infiltrates. ConclusionsWe describe a quantitative platform to enable simultaneous lymphovascular and immune infiltrate analysis and map their spatial relationships in primary melanoma. Our data indicate that tumor-associated vessels exist in different states and that their localization may determine potential for tumor cell exit (metastasis) or leukocyte trafficking (immune response). This platform will support future efforts to map tumor-associated lymphovascular evolution across stage, assess its prognostic value, and stratify patients for adjuvant therapy. TRANSLATIONAL RELEVANCEThis report describes a quantitative, image-based method to investigate the relationship between the tumor-associated lymphovasculature and immune landscape in treatment naive, primary human melanoma. The research shows that melanoma-associated blood and lymphatic vessels display context-dependent phenotypes that associate both with the risk of regional progression and immune infiltration. These findings indicate that stromal/vascular heterogeneity may underlie regional differences in immunogenicity and thus present opportunities for future biomarker development and therapeutic intervention.

cancer biology↗

bioRxiv2021

Infection-induced dermal lymphatic zippering restricts viral dissemination from skin and promotes anti-viral CD8+ T cell expansion.

Lymphatic vessels are often considered passive conduits that rapidly flush antigenic material, pathogens, and cells to draining lymph nodes. Recent evidence, however, suggests that lymphatic vessels actively regulate diverse processes from antigen transport to leukocyte trafficking and dietary lipid absorption. Here we tested the hypothesis that dermal lymphatic transport is dynamic and contributes to innate host defense during viral infection. We demonstrate that cutaneous vaccinia virus infection activates the tightening of lymphatic interendothelial junctions, termed zippering, in a VEGFA/VEGFR2-dependent manner. Both antibody-mediated blockade of VEGFA/VEGFR2 and lymphatic-specific deletion of Vegfr2 impaired lymphatic capillary zippering and increased fluid flux out of tissue. Strikingly, inhibition of lymphatic zippering allows viral dissemination to draining lymph nodes independent of dendritic cell migration and impairs CD8+ T cell priming. These data indicate that infection-induced dermal lymphatic capillary zippering is a context-dependent, active mechanism of innate host defense that limits interstitial fluid and virion flux and promotes protective, anti-viral CD8+ T cell responses. SummaryCutaneous infection with vaccinia virus induces VEGFR2-dependent dermal lymphatic capillary zippering. This tightening of lymphatic junctions exacerbates tissue edema, sequesters virus, and promotes anti-viral CD8+ T cell responses. Dermal lymphatic capillaries are therefore an active component of innate host defense.

immunology↗

bioRxiv2020

A neural crest stem cell-like state drives nongenetic resistance to targeted therapy in melanoma

The ability to predict the future behaviour of an individual cancer is crucial for precision cancer medicine and, in particular, for the development of strategies that prevent acquisition of resistance to anti-cancer drugs. Therapy resistance, which often develops from a heterogeneous pool of drug-tolerant cells known as minimal residual disease (MRD), is thought to mainly occur through acquisition of genetic alterations. Increasing evidence, however, indicates that drug resistance might also be acquired though nongenetic mechanisms. A key emerging question is therefore whether specific molecular and/or cellular features of the MRD ecosystem determine which of these two distinct resistance trajectories will eventually prevail. We show herein that, in melanoma exposed to MAPK-therapeutics, the presence of a neural crest stem cell (NCSC) subpopulation in MRD concurred with the rapid development of resistance through nongenetic mechanisms. Emergence of this drug-tolerant population in MRD relies on a GDNF-dependent autocrine and paracrine signalling cascade, which activates the AKT survival pathway in a Focal-adhesion kinase-(FAK) dependent manner. Ablation of this subpopulation through inhibition of FAK/SRC-signalling delayed relapse in patient-derived tumour xenografts. Strikingly, all tumours that eventually escaped this treatment exhibited resistance-conferring genetic alterations and increased sensitivity to ERK-inhibition. These findings firmly establish that nongenetic reprogramming events contribute to therapy resistance in melanoma and identify a clinically-compatible approach that abrogates such a trajectory. Importantly, these data demonstrate that the cellular composition of MRD deterministically imposes distinct drug resistance evolutionary paths and highlight key principles that may permit more effective pre-emptive therapeutic interventions.

cancer biology↗