Leachman, S. A. | Search bioRxiv

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↗

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↗