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Highly resolved spatial data of complex systems encode rich and nonlinear information. Quantification of heterogeneous and noisy data—often with outliers, artifacts, and mislabeled points—such as those from tissues, remains a challenge. The mathematical field that extracts information from the shape of data, topological data analysis (TDA), has expanded its capability for analyzing real-world datasets in recent years by extending theory, statistics, and computation. An extension to the standard theory to handle heterogeneous data is multiparameter persistent homology (MPH). Here we provide an application of MPH landscapes, a statistical tool with theoretical underpinnings. MPH landscapes, computed for (noisy) data from agent-based model simulations of immune cells infiltrating into a spheroid, are shown to surpass existing spatial statistics and one-parameter persistent homology. We then apply MPH landscapes to study immune cell location in digital histology images from head and neck cancer. We quantify intratumoral immune cells and find that infiltrating regulatory T cells have more prominent voids in their spatial patterns than macrophages. Finally, we consider how TDA can integrate and interrogate data of different types and scales, e.g., immune cell locations and regions with differing levels of oxygenation. This work highlights the power of MPH landscapes for quantifying, characterizing, and comparing features within the tumor microenvironment in synthetic and real datasets.

Physiological effects of cellular hypoxia are sensed by prolyl hydroxylase (PHD) enzymes which regulate HIFs. Genetic interventions on HIF/PHD pathways reveal multiple phenotypes that extend the known biology of hypoxia. Recent studies unexpectedly implicate HIF in aspects of multiple immune and inflammatory pathways. However such studies are often limited by systemic lethal effects and/or use tissue-specific recombination systems, which are inherently irreversible, un-physiologically restricted and difficult to time. To study these processes better we developed recombinant mice which express tetracycline-regulated shRNAs broadly targeting the main components of the HIF/PHD pathway, permitting timed bi-directional intervention. We have shown that stabilization of HIF levels in adult mice through PHD2 enzyme silencing by RNA interference, or inducible recombination of floxed alleles, results in multi-lineage leukocytosis and features of autoimmunity. This phenotype was rapidly normalized on re-establishment of the hypoxia-sensing machinery when shRNA expression was discontinued. In both situations these effects were mediated principally through the Hif2a isoform. Assessment of cells bearing regulatory T cell markers from these mice revealed defective function and pro-inflammatory effects in vivo. We believe our findings have shown a new role for the PHD2/Hif2a couple in the reversible regulation of T cell and immune activity.

Digital pathology enables computational analysis algorithms to be applied at scale to histological images. An example is the identification of immune cells within solid tumours. Image analysis algorithms can extract precise cell locations from immunohistochemistry slides, but the resulting spatial coordinates, or point patterns, can be difficult to interpret. Since localisation of immune cells within tumours may reflect their functional status and correlates with patient prognosis, novel descriptors of their spatial distributions are of biological and clinical interest. A range of spatial statistics have been used to analyse such point patterns but, individually, these approaches only partially describe complex immune cell distributions. In this study, we apply three spatial statistics to locations of CD68+ macrophages within human head and neck tumours, and show that images grouped semi-quantitatively by a pathologist share similar statistics. We generate a synthetic dataset which emulates human samples and use it to demonstrate that combining multiple spatial statistics with a maximum likelihood approach better predicts human classifications than any single statistic. We can also estimate the error associated with our classifications. Importantly, this methodology is adaptable and can be extended to other histological investigations or applied to point patterns outside of histology.

Semaphorin-3A (SEMA3A) functions as a chemorepulsive signal during development and can affect T cells by altering their filamentous actin (F-actin) cytoskeleton. The exact extent of these effects on tumour-specific T cells are not completely understood. Here we demonstrate that Neuropilin-1 (NRP1) and Plexin-A1 and Plexin-A4 are upregulated on stimulated CD8 T cells, allowing tumour-derived SEMA3A to inhibit T cell migration and assembly of the immunological synapse. Deletion of NRP1 in both CD4 and CD8 T cells enhance CD8 T-cell infiltration into tumours and restricted tumour growth in animal models. Conversely, over-expression of SEMA3A inhibit CD8 T-cell infiltration. We further show that SEMA3A affects CD8 T cell F-actin, leading to inhibition of immune synapse formation and motility. Examining a clear cell renal cell carcinoma patient cohort, we find that SEMA3A expression is associated with reduced survival, and that T-cells appear trapped in SEMA3A rich regions. Our study establishes SEMA3A as an inhibitor of effector CD8 T cell tumour infiltration, suggesting that blocking NRP1 could improve T cell function in tumours.

AimTo survey UK cellular pathology departments regarding their attitudes and practices relating to release of human tissue from their diagnostic archives for use in clinical trial research.MethodsA 30-item questionnaire was circulated to the National Cancer Research Institute’s Cellular Molecular Pathology initiative and Confederation of Cancer Biobanks mailing lists. Responses were collected over a 10-month period from November 2016 to August 2017.Results38 departments responded to the survey, the majority of which regularly receive requests for tissue for research purposes. Most requests come from academia and financial support to facilitate tissue release comes from a variety of sources. A range of practices were reported in relation to selection of the most appropriate sample to release, consent checking, costing and governance frameworks.ConclusionsThis survey demonstrates wide variation in practice across the UK and identifies barriers to release of human tissue for clinical trial research. Until we can overcome these obstacles, patient samples will remain inaccessible to research. Therefore, this study highlights the urgent need for clear and coordinated national guidance on this issue.

Semaphorin-3A (SEMA3A) functions as a chemorepulsive signal during development and can affect T cells by altering their filamentous actin (F-actin) cytoskeleton. The exact extent of these effects on tumour-specific T cells are not completely understood. Here we demonstrate that Neuropilin-1 (NRP1) and Plexin-A1 and Plexin-A4 are upregulated on stimulated CD8 + T cells, allowing tumour-derived SEMA3A to inhibit T cell migration and assembly of the immunological synapse. Deletion of NRP1 in both CD4 + and CD8 + T cells enhance CD8 + T-cell infiltration into tumours and restricted tumour growth in animal models. Conversely, over-expression of SEMA3A inhibit CD8 + T-cell infiltration. We further show that SEMA3A affects CD8 + T cell F-actin, leading to inhibition of immune synapse formation and motility. Examining a clear cell renal cell carcinoma patient cohort, we find that SEMA3A expression is associated with reduced survival, and that T-cells appear trapped in SEMA3A rich regions. Our study establishes SEMA3A as an inhibitor of effector CD8 + T cell tumour infiltration, suggesting that blocking NRP1 could improve T cell function in tumours. Interactions between Semaphorin-3A (SEMA3A) and Neuropilin-1 (NRP1) and Plexin-A1 and Plexin-A4 have been shown to affect T cell development. Here the authors investigate how these interactions affect CD8 + T cells in tumour immunity, showing that NRP-1, Plexin-A1 and Plexin-A4 are upregulated on T cells allowing tumour derived SEMA3A to inhibit CD8 + T cell migration and function.

Background Pathology has evolved from a purely morphological description of cellular alterations in disease to our current ability to interrogate tissues with multiple ‘omics’ technologies. By utilising these techniques and others, ‘molecular diagnostics’ acts as the cornerstone of precision/personalised medicine by attempting to match the underlying disease mechanisms to the most appropriate targeted therapy. Methods Despite the promises of molecular diagnostics, significant barriers have impeded its widespread clinical adoption. Thus, the National Cancer Research Institute (NCRI) Cellular Molecular Pathology (CM-Path) initiative convened a national Molecular Diagnostics Forum to facilitate closer collaboration between clinicians, academia, industry, regulators and other key stakeholders in an attempt to overcome these. Results We agreed on a consensus ‘roadmap’ that should be followed during development and implementation of new molecular diagnostic tests. We identified key barriers to efficient implementation and propose possible solutions to these. In addition, we discussed the recent reconfiguration of molecular diagnostic services in NHS England and its likely impacts. Conclusions We anticipate that this consensus statement will provide practical advice to those involved in the development of novel molecular diagnostic tests. Although primarily focusing on test adoption within the United Kingdom, we also refer to international guidelines to maximise the applicability of our recommendations.

We present a case of a 38-year-old woman who presented with symptoms suggestive of intra-abdominal or pelvic malignancy: marked weight loss, abdominal pain, altered bowel habit, anorexia and fatigue. The findings of multiple peritoneal deposits, adnexal and presacral masses on CT imaging and appearances on diagnostic laparotomy also suggested malignancy. However, the histological analysis was inconsistent with malignancy and revealed an infection with Actinomyces israelii. The patient started a course of intravenous antibiotics and complete resolution is expected. An intrauterine contraceptive device was identified as the likely source of the infection.

We present a case of a 38-year-old woman who presented with symptoms suggestive of intra-abdominal or pelvic malignancy: marked weight loss, abdominal pain, altered bowel habit, anorexia and fatigue. The findings of multiple peritoneal deposits, adnexal and presacral masses on CT imaging and appearances on diagnostic laparotomy also suggested malignancy. However, the histological analysis was inconsistent with malignancy and revealed an infection with Actinomyces israelii. The patient started a course of intravenous antibiotics and complete resolution is expected. An intrauterine contraceptive device was identified as the likely source of the infection.