Immune Cell and Cell Cluster Phenotyping, Quantitation, and Visualization Using In Silico Multiplexed Images and Tissue Cytometry

Spleen fibroblastic reticular cell-derived acetylcholine promotes lipid metabolism to drive autoreactive B cell responses

Autoreactive B cell responses are essential for the development of systemic lupus erythematosus (SLE). Fibroblastic reticular cells (FRCs) are known to construct lymphoid compartments and regulate immune functions. Here, we identify spleen FRC-derived acetylcholine (ACh) as a key factor that controls autoreactive B cell responses in SLE. In SLE, CD36-mediated lipid uptake leads to enhanced mitochondrial oxidative phosphorylation in B cells. Accordingly, the inhibition of fatty acid oxidation results in reduced autoreactive B cell responses and ameliorated diseases in lupus mice. Ablation of CD36 in B cells impairs lipid uptake and differentiation of autoreactive B cells during autoimmune induction. Mechanistically, spleen FRC-derived ACh promotes lipid influx and generation of autoreactive B cells through CD36. Together, our data uncover a novel function of spleen FRCs in lipid metabolism and B cell differentiation, placing spleen FRC-derived ACh in a key position in promoting autoreactive B cells in SLE.

Engineering orthotopic tumor spheroids with organ-specific vasculatures for local chemoembolization evaluation

Developing a three-dimensional (3D) in vitro tumor model with vasculature systems suitable for testing endovascular interventional therapies remains a challenge. Here we develop an orthotopic liver tumor spheroid model that captures the organ-level complexity of vasculature systems and the extracellular matrix to evaluate transcatheter arterial chemoembolization (TACE) treatment. The orthotopic tumor spheroids are derived by seeding HepG2 cell colonies with controlled size and location surrounding the portal triads in a decellularized rat liver matrix and are treated by clinically relevant drug-eluting beads embolized in a portal vein vasculature while maintaining dynamic physiological conditions with nutrient and oxygen supplies through the hepatic vein vasculature. The orthotopic tumor model exhibits strong drug retention inside the spheroids and embolization location-dependent cellular apoptosis responses in an analogous manner to in vivo conditions. Such a tumor spheroid model built in a decellularized scaffold containing organ-specific vasculatures, which closely resembles the unique tumor microenvironment, holds the promise to efficiently assess various diagnostic and therapeutic strategies for endovascular therapies.

A comprehensive profile of TCF1+ progenitor and TCF1− terminally exhausted PD-1+CD8+ T cells in head and neck squamous cell carcinoma: implications for prognosis and immunotherapy

The heterogeneity of exhausted T cells (Tex) is a critical determinant of immune checkpoint blockade therapy efficacy. However, few studies have explored exhausted T cell subpopulations in human cancers. In the present study, we examined samples from two cohorts of 175 patients with head and neck squamous cell cancer (HNSCC) by multiplex immunohistochemistry (mIHC) to investigate two subsets of Tex, CD8⁺PD1⁺TCF1⁺ progenitor exhausted T cells (TCF1⁺Tex^prog) and CD8⁺PD1⁺TCF1⁻ terminally exhausted T cells (TCF1⁻Tex^term). Moreover, fresh tumor samples from 34 patients with HNSCC were examined by flow cytometry and immunohistochemistry to further investigate their properties and cytotoxic capabilities and their correlation with regulatory T cells (Tregs) in the tumor immune microenvironment (TIME). mIHC and flow cytometry analysis showed that TCF1⁻Tex^term represented a greater proportion of CD8⁺PD1⁺Tex than TCF1⁺Tex^prog in most patients. TCF1⁺Tex^prog produced abundant TNFα, while TCF1⁻Tex^term expressed higher levels of CD103, TIM-3, CTLA-4, and TIGIT. TCF1⁻Tex^term exhibited a polyfunctional TNFα⁺GZMB⁺IFNγ⁺ phenotype; and were associated with better overall survival and recurrence-free survival. The results also indicated that larger proportions of TCF1⁻Tex^term were accompanied by an increase in the proportion of Tregs. Therefore, it was concluded that TCF1⁻Tex^term was the major CD8⁺PD1⁺Tex subset in the HNSCC TIME and that these cells favor patient survival. A high proportion of TCF1⁻Tex^term was associated with greater Treg abundance.

KDM5B promotes immune evasion by recruiting SETDB1 to silence retroelements

Tumours use various strategies to evade immune surveillance^1,2. Immunotherapies targeting tumour immune evasion such as immune checkpoint blockade have shown considerable efficacy on multiple cancers^3,4 but are ineffective for most patients due to primary or acquired resistance^5-7. Recent studies showed that some epigenetic regulators suppress anti-tumour immunity^2,8-12, suggesting that epigenetic therapies could boost anti-tumour immune responses and overcome resistance to current immunotherapies. Here we show that, in mouse melanoma models, depletion of KDM5B-an H3K4 demethylase that is critical for melanoma maintenance and drug resistance^13-15-induces robust adaptive immune responses and enhances responses to immune checkpoint blockade. Mechanistically, KDM5B recruits the H3K9 methyltransferase SETDB1 to repress endogenous retroelements such as MMVL30 in a demethylase-independent manner. Derepression of these retroelements activates cytosolic RNA-sensing and DNA-sensing pathways and the subsequent type-I interferon response, leading to tumour rejection and induction of immune memory. Our results demonstrate that KDM5B suppresses anti-tumour immunity by epigenetic silencing of retroelements. We therefore reveal roles of KDM5B in heterochromatin regulation and immune evasion in melanoma, opening new paths for the development of KDM5B-targeting and SETDB1-targeting therapies to enhance tumour immunogenicity and overcome immunotherapy resistance.

Tissue Multiplex Analyte Detection in Anatomic Pathology - Pathways to Clinical Implementation

Background: Multiplex tissue analysis has revolutionized our understanding of the tumor microenvironment (TME) with implications for biomarker development and diagnostic testing. Multiplex labeling is used for specific clinical situations, but there remain barriers to expanded use in anatomic pathology practice.

Methods: We review immunohistochemistry (IHC) and related assays used to localize molecules in tissues, with reference to United States regulatory and practice landscapes. We review multiplex methods and strategies used in clinical diagnosis and in research, particularly in immuno-oncology. Within the framework of assay design and testing phases, we examine the suitability of multiplex immunofluorescence (mIF) for clinical diagnostic workflows, considering its advantages and challenges to implementation.

Results: Multiplex labeling is poised to radically transform pathologic diagnosis because it can answer questions about tissue-level biology and single-cell phenotypes that cannot be addressed with traditional IHC biomarker panels. Widespread implementation will require improved detection chemistry, illustrated by InSituPlex technology (Ultivue, Inc., Cambridge, MA) that allows coregistration of hematoxylin and eosin (H&E) and mIF images, greater standardization and interoperability of workflow and data pipelines to facilitate consistent interpretation by pathologists, and integration of multichannel images into digital pathology whole slide imaging (WSI) systems, including interpretation aided by artificial intelligence (AI). Adoption will also be facilitated by evidence that justifies incorporation into clinical practice, an ability to navigate regulatory pathways, and adequate health care budgets and reimbursement. We expand the brightfield WSI system “pixel pathway” concept to multiplex workflows, suggesting that adoption might be accelerated by data standardization centered on cell phenotypes defined by coexpression of multiple molecules.

Conclusion: Multiplex labeling has the potential to complement next generation sequencing in cancer diagnosis by allowing pathologists to visualize and understand every cell in a tissue biopsy slide. Until mIF reagents, digital pathology systems including fluorescence scanners, and data pipelines are standardized, we propose that diagnostic labs will play a crucial role in driving adoption of multiplex tissue diagnostics by using retrospective data from tissue collections as a foundation for laboratory-developed test (LDT) implementation and use in prospective trials as companion diagnostics (CDx).

Next-Generation Digital Histopathology of the Tumor Microenvironment

Progress in cancer research is substantially dependent on innovative technologies that permit a concerted analysis of the tumor microenvironment and the cellular phenotypes resulting from somatic mutations and post-translational modifications. In view of a large number of genes, multiplied by differential splicing as well as post-translational protein modifications, the ability to identify and quantify the actual phenotypes of individual cell populations in situ, i.e., in their tissue environment, has become a prerequisite for understanding tumorigenesis and cancer progression. The need for quantitative analyses has led to a renaissance of optical instruments and imaging techniques. With the emergence of precision medicine, automated analysis of a constantly increasing number of cellular markers and their measurement in spatial context have become increasingly necessary to understand the molecular mechanisms that lead to different pathways of disease progression in individual patients. In this review, we summarize the joint effort that academia and industry have undertaken to establish methods and protocols for molecular profiling and immunophenotyping of cancer tissues for next-generation digital histopathology-which is characterized by the use of whole-slide imaging (brightfield, widefield fluorescence, confocal, multispectral, and/or multiplexing technologies) combined with state-of-the-art image cytometry and advanced methods for machine and deep learning.

Using Cytometry for Investigation of Purinergic Signaling in Tumor-Associated Macrophages

Tumor-associated macrophages are widely recognized for their importance in guiding pro-tumoral or antitumoral responses. Mediating inflammation or immunosuppression, these cells support many key events in cancer progression: cell growth, chemotaxis, invasiveness, angiogenesis and cell death. The communication between cells in the tumor microenvironment strongly relies on the secretion and recognition of several molecules, including damage-associated molecular patterns (DAMPs), such as adenosine triphosphate (ATP). Extracellular ATP (eATP) and its degradation products act as signaling molecules and have extensively described roles in immune response and inflammation, as well as in cancer biology. These multiple functions highlight the purinergic system as a promising target to investigate the interplay between macrophages and cancer cells. Here, we reviewed purinergic signaling pathways connecting cancer cells and macrophages, a yet poorly investigated field. Finally, we present a new tool for the characterization of macrophage phenotype within the tumor. Image cytometry emerges as a cutting-edge tool, capable of providing a broad set of information on cell morphology, expression of specific markers, and its cellular or subcellular localization, preserving cell-cell interactions within the tumor section and providing high statistical strength in small-sized experiments. Thus, image cytometry allows deeper investigation of tumor heterogeneity and interactions between these cells. © 2020 International Society for Advancement of Cytometry.