Examining the variation in consent in general surgery

INTRODUCTION

Consent is a fundamental aspect of surgery and expectations around the consent process have changed following the Montgomery vs Lanarkshire Health Board (2015) court ruling. This study aimed to identify trends in litigation pertaining to consent, explore variation in how consent is practised among general surgeons and identify potential causes of this variation.

METHODS

This mixed-methods study examined temporal variation in litigation rates relating to consent (between 2011 and 2020), using data obtained from National Health Service (NHS) Resolutions. Semi-structured clinician interviews were then conducted to gain qualitative data regarding how general surgeons take consent, their ideologies and their outlook on the recent legal changes. The quantitative component included a questionnaire survey aiming to explore these issues with a larger population to improve the generalisability of the findings.

RESULTS

NHS Resolutions litigation data showed a significant increase in litigation pertaining to consent following the 2015 health board ruling. The interviews demonstrated considerable variation in how surgeons approach consent. This was corroborated by the survey, which illustrated considerable variation in how consent is documented when different surgeons are presented with the same case vignette.

CONCLUSION

A clear increase in litigation relating to consent was seen in the post-Montgomery era, which may be due to legal precedent being established and increased awareness of these issues. Findings from this study demonstrate variability in the information patients receive. In some cases, consent practices did not adequately meet current regulations and therefore are susceptible to potential litigation. This study identifies areas for improvement in the practice of consent.

Mef2c regulates bone mass through Sost-dependent and -independent mechanisms

Mef2c is a transcription factor that mediates key cellular behaviors that promote endochondral ossification and bone formation. Previously, Mef2c has been shown to regulate Sost transcription via its osteocyte-specific enhancer, ECR5, and conditional deletions of Mef2cfl/fl with either Col1-Cre or Dmp1-Cre produced generalized high bone mass (HBM) consistent with Van Buchem Disease phenotypes. However, Sost-/-; Mef2cfl/fl; Dmp1-Cre mice produced a significantly higher bone mass phenotype that Sost-/- alone suggesting that Mef2c modulates bone mass through additional mechanisms, independent of Sost. To identify new Mef2c transcriptional targets important in bone metabolism, we profiled gene expression by single-cell RNA sequencing in subpopulations of cells isolated from Mef2cfl/fl; Dmp1-Cre and Mef2cfl/fl; Bglap-Cre femurs, both strains exhibiting similar high bone mass phenotypes. However, we found Mef2cfl/fl; Bglap-Cre to also display a growth plate defect characterized by an expansion of several osteoprogenitor subpopulations. Differential gene expression analysis identified a total of 96 up- and 2434 down- regulated genes in Mef2cfl/fl; Bglap-Cre and 176 up- and 1041 down- regulated genes in Mef2cfl/fl; Dmp1-Cre bone cell subpopulations compared to wildtype mice. Mef2c deletion affected the transcriptomes across several cell types including mesenchymal progenitors (MP), osteoprogenitors (OSP), osteoblast (OB), and osteocyte (OCY) subpopulations. Several energy metabolism genes such as Uqcrb, Ndufv2, Ndufs3, Ndufa13, Ndufb9, Ndufb5, Cox6a1, Cox5a, Atp5o, Atp5g2, Atp5b, Atp5 were significantly down regulated in Mef2c-deficient OBs and OCYs, in both strains. Binding motif analysis of promoter regions of differentially expressed genes identified Mef2c binding in Bone Sialoprotein (BSP/Ibsp), a gene known to cause increased trabecular BV/TV in the femurs of Ibsp-/- mice. Immunohistochemical analysis confirmed the absence of Ibsp protein in OBs and OCYs. These findings suggests that the HBM in Sost-/-; Mef2cfl/fl; Dmp1-Cre is caused by a multitude of transcriptional changes in genes that regulate bone formation, two of which are Sost and Ibsp.

Loss of Cadherin-11 in pancreatic ductal adenocarcinoma alters tumor-immune microenvironment

Pancreatic ductal adenocarcinoma (PDAC) is one of the top five deadliest forms of cancer with very few treatment options. The 5-year survival rate for PDAC is 10% following diagnosis. Cadherin 11 (Cdh11), a cell-to-cell adhesion molecule, has been suggested to promote tumor growth and immunosuppression in PDAC, and Cdh11 inhibition significantly extended survival in mice with PDAC. However, the mechanisms by which Cdh11 deficiency influences PDAC progression and anti-tumor immune responses have yet to be fully elucidated. To investigate Cdh11-deficiency induced changes in PDAC tumor microenvironment (TME), we crossed p48-Cre; LSL-KrasG12D/+; LSL-Trp53R172H/+ (KPC) mice with Cdh11+/- mice and performed single-cell RNA sequencing (scRNA-seq) of the non-immune (CD45-) and immune (CD45+) compartment of KPC tumor-bearing Cdh11 proficient (KPC-Cdh11+/+) and Cdh11 deficient (KPC-Cdh11+/-) mice. Our analysis showed that Cdh11 is expressed primarily in cancer-associated fibroblasts (CAFs) and at low levels in epithelial cells undergoing epithelial-to-mesenchymal transition (EMT). Cdh11 deficiency altered the molecular profile of CAFs, leading to a decrease in the expression of myofibroblast markers such as Acta2 and Tagln and cytokines such as Il6, Il33 and Midkine (Mdk). We also observed a significant decrease in the presence of monocytes/macrophages and neutrophils in KPC-Cdh11+/- tumors while the proportion of T cells was increased. Additionally, myeloid lineage cells from Cdh11-deficient tumors had reduced expression of immunosuppressive cytokines that have previously been shown to play a role in immune suppression. In summary, our data suggests that Cdh11 deficiency significantly alters the fibroblast and immune microenvironments and contributes to the reduction of immunosuppressive cytokines, leading to an increase in anti-tumor immunity and enhanced survival.

Engineered bone marrow as a clinically relevant ex vivo model for primary bone cancer research and drug screening

Osteosarcoma (OS) is the most common primary malignant bone cancer in children and adolescents. While numerous other cancers now have promising therapeutic advances, treatment options for OS have remained unchanged since the advent of standard chemotherapeutics and offer less than a 25% 5-y survival rate for those with metastatic disease. This dearth of clinical progress underscores a lack of understanding of OS progression and necessitates the study of this disease in an innovative system. Here, we adapt a previously described engineered bone marrow (eBM) construct for use as a three-dimensional platform to study how microenvironmental and immune factors affect OS tumor progression. We form eBM by implanting acellular bone-forming materials in mice and explanting the cellularized constructs after 8 wk for study. We interrogate the influence of the anatomical implantation site on eBM tissue quality, test ex vivo stability under normoxic (5% O2) and standard (21% O2) culture conditions, culture OS cells within these constructs, and compare them to human OS samples. We show that eBM stably recapitulates the composition of native bone marrow. OS cells exhibit differential behavior dependent on metastatic potential when cultured in eBM, thus mimicking in vivo conditions. Furthermore, we highlight the clinical applicability of eBM as a drug-screening platform through doxorubicin treatment and show that eBM confers a protective effect on OS cells that parallel clinical responses. Combined, this work presents eBM as a cellular construct that mimics the complex bone marrow environment that is useful for mechanistic bone cancer research and drug screening.

Vhl deletion in Dmp1 -expressing cells alters MEP metabolism and promotes stress erythropoiesis

In recent years, general hypoxia-inducible factor (HIF)-prolyl hydroxylase (PHD) enzyme inhibitors have been developed for the treatment of anemia due to renal disease and osteoporosis. However, it remains a challenge to target the HIF signaling pathway without dysregulating the skeletal and hematopoietic system. Here, we examined the effects of Vhl deletion in bone by performing longitudinal analyses of Vhl cKO mice at 3, 6, 10, and 24 weeks of age, where at 10 and 24 weeks of age, high bone mass and splenomegaly are present. Using flow cytometry, we observed increased frequency (%) of CD71 lo TER119 hi FSC lo orthochromatophilic erythroblasts and reticulocytes in 10- and 24-week-old Vhl cKO bone marrow (BM), which correlated with elevated erythropoietin levels in the BM and increased number of red blood cells in circulation. The absolute numbers of myeloerythroid progenitors (MEPs) in the BM were significantly reduced at 24 weeks. Bulk RNA-Seq of the MEPs showed upregulation of Epas1 ( Hif1a) and Efnb2 ( Hif2a) in Vhl cKO MEPs, consistent with a response to hypoxia, and genes involved in erythrocyte development, actin filament organization, and response to glucose. Additionally, histological analysis of Vhl cKO spleens revealed red pulp hyperplasia and the presence of megakaryocytes, both of which are features of extramedullary hematopoiesis (EMH). EMH in the spleen was correlated with the presence of mature stress erythroid progenitors, suggesting that stress erythropoiesis is occurring to compensate for the BM microenvironmental irregularities. Our studies implicate that HIF-driven alterations in skeletal homeostasis can accelerate erythropoiesis.

Key Points

• Dysregulation of HIF signaling in Dmp1+ bone cells induces stress erythropoiesis.• Skeletal homeostasis modulates erythropoiesis.

Modulation of Radiation Biomarkers in a Randomized Phase II Study of 131I-MIBG With or Without Radiation Sensitizers for Relapsed or Refractory Neuroblastoma

PURPOSE

¹³¹I-metaiodobenzylguanidine (¹³¹I-MIBG) has demonstrated efficacy as a single agent in neuroblastoma. Recent trials have focused on ¹³¹I-MIBG combination strategies, though little is known about the effect of putative radiosensitizers on biological markers of radiation exposure.

METHODS AND MATERIALS

NANT2011-01 evaluated ¹³¹I-MIBG therapy alone (arm A) or in combination with vincristine/irinotecan (arm B) or vorinostat (arm C) for patients with relapsed or refractory neuroblastoma. Blood samples were collected before and after ¹³¹I-MIBG infusion to determine levels of radiation-associated biomarkers (transcript and protein). The association of biomarker with treatment arm, clinical response, and treatment toxicity was analyzed.

RESULTS

The cohort included 99 patients who had at least 1 biomarker available for analysis. Significant modulation in most biomarkers between baseline, 72, and 96 hours following ¹³¹I-MIBG was observed. Patients in arm C had the lowest degree of modulation in FLT3 ligand protein. Lower baseline BCL2 transcript levels were associated with higher overall response. Patients with greater increases in FLT3 ligand at 96 hours after ¹³¹I-MIBG therapy were significantly more likely to have grade 4 thrombocytopenia. Peripheral blood gene expression of the BCL2 family of apoptotic markers (BCL2L1 and BAX transcripts) was significantly associated with grade 4 hematologic toxicity. RNA sequencing demonstrated little overlap in the top modulated peripheral blood transcripts between randomized arms.

CONCLUSIONS

Peripheral blood biomarkers relevant to radiation exposure demonstrate significant modulation after ¹³¹I-MIBG and concomitant radiation sensitizers affect extent of modulation. Biomarkers related to hematopoietic damage and apoptosis were associated with hematologic toxicity.

Isolation of Murine Articular Chondrocytes for Single-Cell RNA or Bulk RNA Sequencing Analysis

Single-cell RNA sequencing (scRNA-seq) is highly dependent on cellular composition of a tissue of interest. For soft tissues, isolation of individual cells from the extracellular matrix (ECM) while retaining viability and minimizing degradation within subpopulations is well established. In contrast, articular cartilage is comprised of sparsely positioned chondrocytes embedded within a dense ECM high in glycosaminoglycans, proteoglycans, and many fibrous proteins such as collagens, elastin, fibronectin, and laminins. This densely packed ECM makes it difficult to isolate viable chondrocytes for further single-cell analysis. This protocol highlights a successful technique optimized for isolating chondrocytes from the articulated joints of rodent animal models using a series of enzymatic digestions and chondrocyte enrichment using a double negative selection process through florescence-activated cell sorting (FACS).

Dose-dependent consequences of sub-chronic fentanyl exposure on neuron and glial co-cultures

Fentanyl is one of the most common opioid analgesics administered to patients undergoing surgery or for chronic pain management. While the side effects of chronic fentanyl abuse are recognized (e.g., addiction, tolerance, impairment of cognitive functions, and inhibit nociception, arousal, and respiration), it remains poorly understood what and how changes in brain activity from chronic fentanyl use influences the respective behavioral outcome. Here, we examined the functional and molecular changes to cortical neural network activity following sub-chronic exposure to two fentanyl concentrations, a low (0.01 μM) and high (10 μM) dose. Primary rat co-cultures, containing cortical neurons, astrocytes, and oligodendrocyte precursor cells, were seeded in wells on either a 6-well multi-electrode array (MEA, for electrophysiology) or a 96-well tissue culture plate (for serial endpoint bulk RNA sequencing analysis). Once networks matured (at 28 days in vitro), co-cultures were treated with 0.01 or 10 μM of fentanyl for 4 days and monitored daily. Only high dose exposure to fentanyl resulted in a decline in features of spiking and bursting activity as early as 30 min post-exposure and sustained for 4 days in cultures. Transcriptomic analysis of the complex cultures after 4 days of fentanyl exposure revealed that both the low and high dose induced gene expression changes involved in synaptic transmission, inflammation, and organization of the extracellular matrix. Collectively, the findings of this in vitro study suggest that while neuroadaptive changes to neural network activity at a systems level was detected only at the high dose of fentanyl, transcriptomic changes were also detected at the low dose conditions, suggesting that fentanyl rapidly elicits changes in plasticity.

Abstract P1115: SnoRNAs As Potential Biomarkers For Assessment Of Health Risks In Astronauts

During spaceflight, astronauts are exposed to various physiological and psychological stressors, such as microgravity, sleep deprivation, isolation, confinement, and high ionizing radiation have shown adverse health effects. Therefore, there is an unmet need to develop novel diagnostic tools to predict early alterations in astronauts' health. Small nucleolar RNA (snoRNA) is a type of short ncRNAs (60-300 nucleotides) known to guide 2’-O-methylation (Nm) or pseudouridine (ψ) on ribosomal RNA (rRNA), snRNA, or mRNA. Emerging evidence suggests that dysregulated snoRNAs may be key players in regulating fundamental cellular mechanisms and the pathogenesis of cancer, heart, and neurological disease. Therefore, we sought to determine whether the spaceflight-induced snoRNA changes in plasma extracellular vesicles (EV) and astronaut's peripheral blood mononuclear cells (PBMCs) can be utilized as potential biomarkers. Using unbiased small RNA sequencing (sRNAseq), we evaluated the EV snoRNA changes in peripheral blood (PB) plasma of astronauts (n=5/group) who underwent median 12-day long Shuttle missions between 1998-2001. Using stringent cutoff (> log 2-fold change, FDR < 0.05), we detected 20 down-regulated snoRNAs and 10 upregulated PB-EVs at R+3 compared to L-10. qPCR validation revealed that SNORA74A was significantly down-regulated at R+3 compared to L-10. We next determined snoRNA expression levels in astronauts' PBMCs at R+3 and L-10 (n=6/group). qPCR analysis further confirmed a significant increase in SNORA19 and SNORA47 in astronauts' PBMCs at R+3 compared to L-10 Notably, many downregulated snoRNA-guided rRNA modifications, including four Nms and five ψs. Our findings unveiled that spaceflight induced changes in EV and PBMCs snoRNA expression, thus suggesting snoRNAs may serve as novel biomarkers for monitoring astronauts' health.

Single-cell RNA-Seq reveals changes in immune landscape in post-traumatic osteoarthritis

Osteoarthritis (OA) is the most common joint disease, affecting over 300 million people world-wide. Accumulating evidence attests to the important roles of the immune system in OA pathogenesis. Understanding the role of various immune cells in joint degeneration or joint repair after injury is vital for improving therapeutic strategies for treating OA. Post-traumatic osteoarthritis (PTOA) develops in ~50% of individuals who have experienced an articular trauma like an anterior cruciate ligament (ACL) rupture. Here, using the high resolution of single-cell RNA sequencing, we delineated the temporal dynamics of immune cell accumulation in the mouse knee joint after ACL rupture. Our study identified multiple immune cell types in the joint including neutrophils, monocytes, macrophages, B cells, T cells, NK cells and dendritic cells. Monocytes and macrophage populations showed the most dramatic changes after injury. Further characterization of monocytes and macrophages reveled 9 major subtypes with unique transcriptomics signatures, including a tissue resident Lyve1hiFolr2hi macrophage population and Trem2hiFcrls+ recruited macrophages, both showing enrichment for phagocytic genes and growth factors such as Igf1, Pdgfa and Pdgfc. We also identified several genes induced or repressed after ACL injury in a cell type-specific manner. This study provides new insight into PTOA-associated changes in the immune microenvironment and highlights macrophage subtypes that may play a role in joint repair after injury.

IL-17A Increases Doxorubicin Efficacy in Triple Negative Breast Cancer

Due to lack of targetable receptors and intertumoral heterogeneity, triple negative breast cancer (TNBC) remains particularly difficult to treat. Doxorubicin (DOX) is typically used as nonselective neoadjuvant chemotherapy, but the diversity of treatment efficacy remains unclear. Comparable to variability in clinical response, an experimental model of TNBC using a 4T1 syngeneic mouse model was found to elicit a differential response to a seven-day treatment regimen of DOX. Single-cell RNA sequencing identified an increase in T cells in tumors that responded to DOX treatment compared to tumors that continued to grow uninhibited. Additionally, compared to resistant tumors, DOX sensitive tumors contained significantly more CD4 T helper cells (339%), γδ T cells (727%), Naïve T cells (278%), and activated CD8 T cells (130%). Furthermore, transcriptional profiles of tumor infiltrated T cells in DOX responsive tumors revealed decreased exhaustion, increased chemokine/cytokine expression, and increased activation and cytotoxic activity. γδ T cell derived IL-17A was identified to be highly abundant in the sensitive tumor microenvironment. IL-17A was also found to directly increase sensitivity of TNBC cells in combination with DOX treatment. In TNBC tumors sensitive to DOX, increased IL-17A levels lead to a direct effect on cancer cell responsiveness and chronic stimulation of tumor infiltrated T cells leading to improved chemotherapeutic efficacy. IL-17A’s role as a chemosensitive cytokine in TNBC may offer new opportunities for treating chemoresistant breast tumors and other cancer types.

Spaceflight-Associated Changes of snoRNAs in Peripheral Blood Mononuclear Cells and Plasma Exosomes—A Pilot Study

During spaceflight, astronauts are exposed to various physiological and psychological stressors that have been associated with adverse health effects. Therefore, there is an unmet need to develop novel diagnostic tools to predict early alterations in astronauts’ health. Small nucleolar RNA (snoRNA) is a type of short non-coding RNA (60–300 nucleotides) known to guide 2′-O-methylation (Nm) or pseudouridine (ψ) of ribosomal RNA (rRNA), small nuclear RNA (snRNA), or messenger RNA (mRNA). Emerging evidence suggests that dysregulated snoRNAs may be key players in regulating fundamental cellular mechanisms and in the pathogenesis of cancer, heart, and neurological disease. Therefore, we sought to determine whether the spaceflight-induced snoRNA changes in astronaut’s peripheral blood (PB) plasma extracellular vesicles (PB-EV) and peripheral blood mononuclear cells (PBMCs). Using unbiased small RNA sequencing (sRNAseq), we evaluated changes in PB-EV snoRNA content isolated from astronauts (n = 5/group) who underwent median 12-day long Shuttle missions between 1998 and 2001. Using stringent cutoff (fold change > 2 or log₂-fold change >1, FDR < 0.05), we detected 21 down-and 9—up-regulated snoRNAs in PB-EVs 3 days after return (R + 3) compared to 10 days before launch (L-10). qPCR validation revealed that SNORA74A was significantly down-regulated at R + 3 compared to L-10. We next determined snoRNA expression levels in astronauts’ PBMCs at R + 3 and L-10 (n = 6/group). qPCR analysis further confirmed a significant increase in SNORA19 and SNORA47 in astronauts’ PBMCs at R + 3 compared to L-10. Notably, many downregulated snoRNA-guided rRNA modifications, including four Nms and five ψs. Our findings revealed that spaceflight induced changes in PB-EV and PBMCs snoRNA expression, thus suggesting snoRNAs may serve as potential novel biomarkers for monitoring astronauts’ health.

Astronauts Plasma-Derived Exosomes Induced Aberrant EZH2-Mediated H3K27me3 Epigenetic Regulation of the Vitamin D Receptor

There are unique stressors in the spaceflight environment. Exposure to such stressors may be associated with adverse effects on astronauts' health, including increased cancer and cardiovascular disease risks. Small extracellular vesicles (sEVs, i.e., exosomes) play a vital role in intercellular communication and regulate various biological processes contributing to their role in disease pathogenesis. To assess whether spaceflight alters sEVs transcriptome profile, sEVs were isolated from the blood plasma of 3 astronauts at two different time points: 10 days before launch (L-10) and 3 days after return (R+3) from the Shuttle mission. AC16 cells (human cardiomyocyte cell line) were treated with L-10 and R+3 astronauts-derived exosomes for 24 h. Total RNA was isolated and analyzed for gene expression profiling using Affymetrix microarrays. Enrichment analysis was performed using Enrichr. Transcription factor (TF) enrichment analysis using the ENCODE/ChEA Consensus TF database identified gene sets related to the polycomb repressive complex 2 (PRC2) and Vitamin D receptor (VDR) in AC16 cells treated with R+3 compared to cells treated with L-10 astronauts-derived exosomes. Further analysis of the histone modifications using datasets from the Roadmap Epigenomics Project confirmed enrichment in gene sets related to the H3K27me3 repressive mark. Interestingly, analysis of previously published H3K27me3–chromatin immunoprecipitation sequencing (ChIP-Seq) ENCODE datasets showed enrichment of H3K27me3 in the VDR promoter. Collectively, our results suggest that astronaut-derived sEVs may epigenetically repress the expression of the VDR in human adult cardiomyocytes by promoting the activation of the PRC2 complex and H3K27me3 levels.

Abstract 3136: Molecular characterization of the effects of cancer-derived exosomes on murine lung cancer tumors

Lung cancer is the second most diagnosed type of cancer and is the leading cause of cancer-related deaths in both men and women. An estimated 235,760 new cases of lung cancer and 131,880 lung cancer deaths are expected this year accounting for 12% of new cancer cases and 22% of cancer deaths in the United States. Exosomes are secreted vesicles that contain selectively packaged biomaterials (protein, lipids, and RNA) and serve as a form of extracellular communication between cells in the tumor microenvironment. Previous studies have shown the effects of cancer-derived exosomes on specific cell types or gross tumor response in vivo yet, the competitive nature and dynamics of exosomal uptake in the tumor microenvironment remains largely unknown. This work seeks to identify molecular responses induced by cancer-derived exosomes on cells residing in the tumor microenvironment.

In order to control tumor cell exposure to cancer-derived exosomes, heterogeneous ex vivo cultures derived from subcutaneous Lewis lung carcinoma (LLC) tumors in C57BL6 mice were exposed to fluorescently dyed LLC exosomes for up to 72 hours. Flow cytometric analysis was performed to identify preferential uptake of cancer exosomes into the stromal subpopulations of tumor cells. Increased uptake was observed throughout the duration of the exposure and preferential uptake was observed into neutrophils, macrophages, and endothelial cells while cancer cells, fibroblasts, and lymphocytes were underrepresented in the exosome uptaken population. Additionally, single cell RNA-sequencing was performed 24 hours post-exosomal exposure to identify transcriptional changes promoted by cancer exosome uptake. We found tumor-derived cancer cells to up-regulate transcripts associated with proliferation and down-regulated genes associated with interferon signaling in response to exosome uptake.

These preliminary findings suggest that cancer-derived exosomes have targeted effects on specific cell types in the tumor microenvironment. Specifically in cancer cells, exosomal uptake can elicit protumor (cancer proliferation and immune suppression via decreased interferon signaling) effects that may serve as mediators of disease progression. An understanding of both cancer and host-derived exosomal response to disease progression may identify novel biomarkers and potential therapeutic targets previously undiscovered using canonical discovery methods.

This study received funding from LLNL LDRD grant 21-LW-028. This work was conducted under the auspices of the USDOE by LLNL (DE-AC52-07NA27344). LLNL-ABS-829271

Citation Format: Nicholas R. Hum, Nicole F. Leon, Aimy Sebastian, Kelly A. Martin, Gabriela G. Loots. Molecular characterization of the effects of cancer-derived exosomes on murine lung cancer tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3136.

Abstract 2516: Loss of cadherin 11 in pancreatic cancer induces altered immune cell infiltration

Pancreatic ductal adenocarcinoma (PDAC) is one of the top five deadliest forms of cancer with very few treatment options. The 5-year survival rate for PDAC is 10% following diagnosis. Preclinical murine models have been developed that leverage key driver mutations and have significantly contributed to our understanding of PDAC. One such genetically engineered mouse model (GEMM) that has emerged as an important tool is the KPC mouse (LSL-KrasG12D/+;LSL-Trp53R172H/+; p48-Cre) that spontaneously develops pancreatic tumors at ~14-16 weeks of age. Cadherin-11 (Cdh11), a cell-to-cell adhesion molecule has been suggested to play a role in development of the desmoplastic stroma in PDAC, that leads to difficulties in drug accessibility and has been hypothesized to contribute to chemotherapeutic resistance and correlate with poor prognosis. However, the mechanisms by which Cdh11 deficiency in the stromal microenvironment of PDAC-bearing KPC mice influences tumor infiltrating immune cells, has yet to be fully understood. Single-cell RNA sequencing (scRNAseq) of the immune (CD45+) compartment of tumor bearing Cdh11 proficient (KPC/Cdh11+/+), tumor bearing Cdh11 deficient (KPC/Cdh11+/-), non-tumor bearing Cdh11 deficient (Cdh11+/-) and wildtype (Cdh11+/+) mice was performed. We observed a sharp decrease in the presence of myeloid/monocyte lineage cells (CD14+) in KPC/Cdh11+/- tumors and also an increase in T, B and plasma cells, compared to KPC/Cdh11+/+ tumors. Genes upregulated in infiltrating T- and NK cells specific to a Cdh11 deficient background include Cd8a, Nkg7, Maf. Additionally, genes found to be upregulated in B cell clusters in Cdh11 deficient mice include those related to B cell differentiation/activation such as Lgals1, Id2, Itgb1, Rgs1. The increase in B and T cell infiltration was specific to the Cdh11 deficient background, since both pancreata from KPC/Cdh11+/+and Cdh11+/- mice had elevated levels of infiltration. Immunohistochemical validation of these findings has confirmed these changes in tumor infiltrating immune cells. Additionally of note, an increase in antibody-producing plasma cells was observed specifically in a Cdh11 deficient background. Igkc, an immunoglobulin found to be enriched in plasma cells was highly expressed in this group of immune cells. We also observed that KPC/Cdh11+/-had significantly more Igkc expressing cells than KPC/Cdh11+/+. Future work is needed to clearly define the role of Cdh11 in modulating B, T and plasma cell behavior and subsequent contributions to PDAC outcome. This study received funding by LDRD 19-SI-003. This work was conducted under the auspices of the USDOE by LLNL (DE-AC52-07NA27344), LLNL-ABS-820889. This work was supported by AACR-AstraZeneca Fellowship in Immunooncology Research, grant 17-40-12-PERA; The Ruesch Center for the Cure of Gastrointestinal Cancers grant award; NIH R01 CA170653; and NIH Cancer Center Support Grant P30 CA051008.

Citation Format: Kelly A. Martin, Aimy Sebastian, Nicholas Hum, Ivana Peran, Stephen Byers, Elizabeth Wheeler, Matthew Coleman, Gabriela Loots. Loss of cadherin 11 in pancreatic cancer induces altered immune cell infiltration [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2516.

POS0818 SOUTHEND PRE-TEST PROBABILITY SCORE AND HALO SCORE AS MARKERS FOR DIAGNOSIS AND MONITORING OF GCA: EARLY RESULTS FROM THE PROSPECTIVE HAS-GCA STUDY

Background

Ultrasound (US) is recommended as the first line imaging test in patients with suspected Giant Cell Arteritis (GCA). Traditionally, the US halo sign has been used for diagnosis. We have recently described a composite Halo Score that allows to quantify vascular inflammation on US. Prospective studies on response and disease monitoring are lacking.

Objectives

To prospectively assess the role of US in diagnosing and monitoring GCA patients. We report early baseline and 12-month data on our current recruitment in a study that has suffered disruption from the pandemic.

Methods

HAS GCA (IRAS#264294) is an ongoing, prospective, multicentre study recruiting from referrals of suspected GCA to fast-track clinics. Based on the Southend GCA clinical pre-test probability score (SPTPS)1, patients were stratified in to low, intermediate and high risk categories2. Temporal and axillary US Halo Scores were calculated from the halo thickness and extent in bilateral temporal arteries, parietal and frontal branches (TAHS) and axillary arteries (AAHS). These scores were summed (TAHS x1 plus; AAHS x3) to generate a Total Halo Score (THS)3.

Mann Whitney U test was used to compare baseline features between GCA and controls. Wilcoxon signed rank test was used to evaluate disease features at baseline and at 12 months in GCA patients. Sensitivity (Sn), Specificity (Sp) and ROC curve were calculated, where applicable. P value <0.05 is statistically significant

Results

202 patients (71 GCA, 131 controls) have been recruited thus far: 23 completed 12-month follow up assessment; 6 were lost to follow up (4 died, 2 withdrew consent due to pandemic). Demographics, clinical features, and US results are shown (Table 1).

Table 1.

Baseline features of GCA patients and controls

GCA (n=71)Controls (n=131)P-valueAge, median (IQR)75 (70-81)68 (62-76)0.001Female, n (%)38 (54)89 (68)0.05SPTPS category, n (%) Low risk0 (0)59 (45)<0.001 Intermediate risk16 (23)49 (37)0.04 High risk55 (77)23 (18)<0.001Halo score (HS), median (range) Temporal artery HS12 (0-22)2 (0-17)<0.0001 Axillary artery HS12 (0-21)6 (0-18)<0.0001 Total HS21 (2-40)8 (0-29)<0.0001Clinical features, n (%) Temporal headache53 (75)93 (71)0.62 Scalp tenderness36 (51)40 (31)0.006 Jaw claudication38 (54)9 (7)<0.001 PMR symptoms29 (41)35 (27)0.06 Constitutional symptoms42 (59)29 (22)<0.001 Visual disturbance40 (56)58 (44)0.11 Vision loss21 (30)9 (7)<0.001

AA, axillary artery; GCA, Giant cell arteritis; TA, Temporal artery

Among GCA patients, 50 had cranial, 5 large-vessel and 16 mixed phenotypes. Diseases were diagnosed by US and additional tests such as PET CT.

Jaw claudication (54%) and constitutional symptoms (59%) were the dominant features in GCA patients. Median age was 75 years in GCA (54% females) and 68 years in controls (68% females). GCA and controls were stratified by SPTPS to Low risk (0% vs 45%; Sn-undefined, Sp-98), Intermediate risk (23% vs 37%; Sn-81, Sp-98) and High risk (77% vs 18%; Sn-98, Sp-91). Optimal SPTPS cut-off point was ≥12 (Sn-89, Sp-76).

Median THS was 21 in GCA and 8 in controls. Optimal cut-off Halo Score in diagnosis was TAHS ≥5 (Sn-89, Sp-86), AAHS ≥11 (Sn-55, Sp-75), THS ≥15 (Sn-79%, Sp-86%). Baseline Halo Score and CRP levels showed positive correlation (spearman rank correlation). Among the 23 patients who completed 12-months follow up, median TAHS, AAHS and THS reduced from 12 to 2, 12 to 6 and 21 to 10, respectively (Figure 1).

Conclusion

Along with SPTPS, Halo Score successfully discriminates GCA from non GCA mimics and. HS is effective in showing 12-month response. This score may be a useful marker to monitor GCA disease activity

References

[1]Laskou F et al. Clin Exp Rheumatol. 2019

[2]Sebastian A et al. RMD Open. 2020

[3]Sebastian A et al. BMC Rheumatol. 2020

Disclosure of Interests

Alwin Sebastian: None declared, Alessandro Tomelleri: None declared, Pierluigi Macchioni: None declared, Giulia Klinowski: None declared, Carlo Salvarani: None declared, Abdul Kayani: None declared, Mohammad Tariq: None declared, Diana Prieto-Peña: None declared, Edoardo Conticini: None declared, Muhammad Khurshid: None declared, Sue Inness: None declared, Jo Jackson: None declared, Kornelis van der Geest Speakers bureau: Roche, Grant/research support from: Mandema stipend, Bhaskar Dasgupta: None declared

MAVS mediates a protective immune response in the brain to Rift Valley fever virus

Rift Valley fever virus (RVFV) is a highly pathogenic mosquito-borne virus capable of causing hepatitis, encephalitis, blindness, hemorrhagic syndrome, and death in humans and livestock. Upon aerosol infection with RVFV, the brain is a major site of viral replication and tissue damage, yet pathogenesis in this organ has been understudied. Here, we investigated the immune response in the brain of RVFV infected mice. In response to infection, microglia initiated robust transcriptional upregulation of antiviral immune genes, as well as increased levels of activation markers and cytokine secretion that is dependent on mitochondrial antiviral-signaling protein (MAVS) and independent of toll-like receptors 3 and 7. In vivo, Mavs^-/- mice displayed enhanced susceptibility to RVFV as determined by increased brain viral burden and higher mortality. Single-cell RNA sequence analysis identified defects in type I interferon and interferon responsive gene expression within microglia in Mavs^-/- mice, as well as dysregulated lymphocyte infiltration. The results of this study provide a crucial step towards understanding the precise molecular mechanisms by which RVFV infection is controlled in the brain and will help inform the development of vaccines and antiviral therapies that are effective in preventing encephalitis.

Rift Valley fever virus causes severe disease in humans and livestock and in some cases can be fatal. There is concern about the use of Rift Valley fever virus as a bioweapon since it can be transmitted through the air, and there are no vaccines or antiviral treatments. Airborne transmission of the virus causes severe inflammation of the brain, yet little is known about the immune response against the virus in this organ. Here, we investigated the immune response in the brain to Rift Valley fever virus following intranasal infection. We determined that microglia, the resident immune cells of the brain, initiate a robust response to Rift Valley fever virus infection and identified a key immune pathway that is critical for the ability of microglia to respond to infection. When this immune pathway is rendered non-functional, mice have a dysregulated response to infection in the brain. This study provides insight into how the immune response can control Rift Valley fever virus infection of the brain.

Altered canalicular remodeling associated with femur fracture in mice

We previously showed that femur fracture in mice caused a reduction in bone volume at distant skeletal sites within 2 weeks post-fracture. Osteocytes also have the ability to remodel their surrounding bone matrix through perilacunar/canalicular remodeling (PLR). If PLR is altered systemically following fracture, this could affect bone mechanical properties and increase fracture risk at all skeletal sites. In this study, we investigated whether lacunar-canalicular microstructure and the rate of PLR are altered in the contralateral limb following femoral fracture in mice. We hypothesized that femoral fracture would accelerate PLR by 2 weeks postfracture, followed by partial recovery by 4 weeks. We used histological evaluation and high-resolution microcomputed tomography to quantify the morphology of the lacunar-canalicular network at the contralateral tibia, and we used quantitative real-time polymerase chain reaction (RT-PCR) and RNA-seq to measure the expression of PLR-associated genes in the contralateral femur. We found that at both 2 and 4 weeks postfracture, canalicular width was significantly increased by 18.6% and 16.6%, respectively, in fractured mice relative to unfractured controls. At 3 days and 4 weeks post-fracture, we observed downregulation of PLR-associated genes; RNA-seq analysis at 3 days post-fracture showed a deceleration of bone formation and mineralization in the contralateral limb. These data demonstrate notable canalicular changes following fracture that could affect bone mechanical properties. These findings expand our understanding of systemic effects of fracture and how biological and structural changes at distant skeletal sites may contribute to increased fracture risk following an acute injury.

Extracellular matrix modulates T cell clearance of malignant cells in vitro

Despite the success of T cell checkpoint therapies, breast cancers rarely express these immunotherapy markers and are believed to be largely "immune cold" with limited inflammation and immune activation. The reason for this limited immune activation remains poorly understood. We sought to determine whether extracellular matrix substrate could contribute to this limited immune activation. Specifically, we asked whether extracellular matrix could alter T cell cytotoxicity against malignant mammary gland carcinoma cells (MCC) in a setup designed to promote maximal T cell efficacy (i.e., rich media with abundant IL2, high ratio of T cells to MCC). We observed that T cell clearance of MCC varied from 0% in collagen 4 or 6 conditions to almost 100% in fibronectin or vitronectin. Transcriptomics revealed that T cell function was defective in MCC/T cell cocultures on collagen 4 (Col4), potentially corresponding to greater expression of cytokines MCC cultured in this environment. In contrast, transcriptomics revealed an effective, exhausted phenotype on vitronectin. The observation that Col4 induces T cell suppression suggests that targeting tumor-ECM interactions may permit new approaches for utilizing immunotherapy in tumors which do not provoke a strong immune response.

Emerging Role of Exosomal Long Non-coding RNAs in Spaceflight-Associated Risks in Astronauts

During spaceflight, astronauts are exposed to multiple unique environmental factors, particularly microgravity and ionizing radiation, that can cause a range of harmful health consequences. Over the past decades, increasing evidence demonstrates that the space environment can induce changes in gene expression and RNA processing. Long non-coding RNA (lncRNA) represent an emerging area of focus in molecular biology as they modulate chromatin structure and function, the transcription of neighboring genes, and affect RNA splicing, stability, and translation. They have been implicated in cancer development and associated with diverse cardiovascular conditions and associated risk factors. However, their role on astronauts' health after spaceflight remains poorly understood. In this perspective article, we provide new insights into the potential role of exosomal lncRNA after spaceflight. We analyzed the transcriptional profile of exosomes isolated from peripheral blood plasma of three astronauts who flew on various Shuttle missions between 1998-2001 by RNA-sequencing. Computational analysis of the transcriptome of these exosomes identified 27 differentially expressed lncRNAs with a Log2 fold change, with molecular, cellular, and clinical implications.

Abstract P043: Extracellular matrix modulates T cell clearance of malignant cells in vitro

Introduction: Emerging evidence suggests that tumor extracellular matrix (ECM) may play a role in tumor-immune interactions. Breast tumors with high immune infiltrates have a distinct ECM profile, and T cell exclusion has been linked to specific ECM signatures. Despite this evidence suggesting a link between immune infiltrates and tumor matrix, it remains unclear whether ECM can directly affect the ultimate step in tumor clearance by the immune system, T cell mediated cytotoxicity.

Methods: We compared clearance of 4T1 mammary gland carcinoma cells (MCC) seeded on ECM arrays by T cells isolated from spleens of MHC mismatched strain of mice. Briefly, 4T1 were seeded at 10k/ml for 1 hour, cultured for 24 hours then cocultured with T cells for 2 hours before fixing and staining. For RNA sequencing, ECM proteins (Collagen 1 -Col1, Collagen 4- Col4, Fibronectin -Fn or Vitronectin- Vtn) were coated onto plates at 250ug/ml, then 4t1 were added for 24 hours, then T cells were added for 24 hours followed by RNA isolation and sequencing.

Results: We compared number of cells per spot with and without T cells across all ECM combinations and found that co-culture with T cells reduced the average number of MCCs, but this difference did not reach statistical significance. Only in the following conditions did MCC number significantly decrease: Col1 alone, Col6 alone, Fn alone, Vtn alone and Col6+ Eln (Fig 2B). In Col4 containing conditions, MCC cell number increased in the presence of T cells. Intensity of CD274 (PD-L1) and the MHC class 1 protein H2-Kd varied with substrate (p&lt;10−19, p&lt;10−22 respectively) with significantly higher expression of PD-L1 in Col1 and Vtn conditions vs. Col4 or Laminin, and higher H2-Kd in Vtn conditions. These findings demonstrate a defect in T cell mediated MCC clearance in some ECM conditions that is distinct from the PD-L1 checkpoint. Comparing transcriptomes across, we observed that all MCC+ T cell conditions separated from MCC alone conditions (Fig. 3B), largely due to expression of known T cell related genes (such as Ptprc, Trbc2, Sell, Itk, and Il7r). Differentially regulated gene counts between MCC+ T cells and MCC alone conditions were lowest in the Col4 condition (Fig. 3BC-E), and significance and number of genes from T cell associated ontologies were lowest in the Col4 conditions (Fig. 3E). We observed that MCC on Col4 upregulated cytokines including Ccl2, Cxcl3, Cxcl10, and Tgfβ2, compared to both Fn and Vtn conditions, suggesting that this condition could suppress immune activation through altered cytokine expression.

This work was funded by LDRD 19-SI-003 under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. LLNL-ABS-8235222

Citation Format: Claire Robertson, Aimy Sebastian, Aubree Hinckley, Naiomy Rios-Arce, William Hynes, Wei He, Nicholas Hum, Elizabeth Wheeler, Gabriela Loots, Matthew Coleman, Monica Moya. Extracellular matrix modulates T cell clearance of malignant cells in vitro [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2021 Oct 5-6. Philadelphia (PA): AACR; Cancer Immunol Res 2022;10(1 Suppl):Abstract nr P043.

Abstract 2638: Developing 3d hydrogel model for patient-derived organoids of metastatic colorectal cancer

The advances in the development of preclinical models for various cancers have tremendously helped study of the biology and genetics of human cancers as well as for development of therapeutics. Recently, patient-derived organoids (PDOs) have emerged as a robust preclinical platform that can provide insight into the patient specific genetic mechanisms, cancer progression and drug susceptibility. We have developed a novel PDO platform by embedding patient-derived organoids in a 3D hydrogel suspension culture. Our previous studies have shown that, when cultured in hydrogel, spheroids derived from cancer cell lines demonstrated upregulated gene expression signatures in relation to migration and angiogenesis compared to cultures in media, suggesting a more hypoxic, nutrient deficient environment. Given that hypoxia and nutrient deficiency are important feathers of solid tumors, the hydrogel environment could provide a good platform for in vitro study of tumor development and resistance to treatment. In the current study, we embedded PDOs derived from liver metastasis of colorectal cancer into the 3D suspension hydrogel culture. The PDOs adapted well in the hydrogel gel environment. We assessed the response of PDOs in hydrogel to anticancer agents, and compared that to those cultured in media. The PDOs cultured in hydrogel showed significantly elevated resistance to the treatments. The IC50s of chemotherapeutic drugs 5-fluorouracil and oxaliplatin are increased by ~5-10 fold when cultured in hydrogel compared to those in media. Further studies through RNAseq analysis revealed differentially activated signaling pathways. In particular, the levels of the CXC ligand family chemokines are significantly up-regulated in the PDOs cultured in the hydrogel. The CXC ligand family chemokines are important immune stimulants that are known to play key role in the chemotaxis and tumor recruitment of immune cells including neutrophil, T-cell and B-cells. Interestingly, the elevated levels of CXC-ligands have been shown to relate to resistance of colorectal cancer against drug treatment such as 5-fluorouracil. Our hydrogel model could help elucidate the mechanisms behind such resistance. Future study will focus on evaluating how well the hydrogel PDO platform can recapitulate tumor microenvironment and its potential in screening for personalized medicine.

Citation Format: He Wei, Eveliina Karelehto, Karen Dubbin, Aimy Sebastian, Robert Warren, Monica Moya, Gaby Loots, Elizabeth Wheeler, Matthew Coleman. Developing 3d hydrogel model for patient-derived organoids of metastatic colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2638.

Abstract 2741: Loss of Cadherin-11 in PDAC induces altered immune cell infiltration and remodels stromal landscape

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal forms of cancer with very few treatment options. Less than 10 percent of patients diagnosed with PDAC survive 5 years post diagnosis. Mutations in CDKN2A, SMAD4, KRAS and P53 have been well linked to the development of PDAC. Preclinical murine models have been developed that leverage key driver mutations and have significantly contributed to our understanding of PDAC. One such genetically engineered mouse model (GEMM) that has emerged as an important tool in PDAC investigations is the KPC mouse (LSL-KrasG12D/+LSL-Trp53R172H/+Pdx-1-Cre) that spontaneously develops pancreatic tumors at ~14-16 weeks of age. Cadherin-11 (Cdh11), a cell-to-cell adhesion molecule, is highly expressed in desmoplastic stroma, a characteristic of PDAC, that leads to difficulties in drug accessibility and has been hypothesized to contribute to chemotherapeutic resistance. However, the mechanisms by which Cdh11 deficiency in the stromal microenvironment of PDAC-bearing mice (KPC) influences therapeutic outcomes, has yet to be fully understood. Single-cell RNA sequencing (scRNAseq) of both the non-immune (CD45-) and immune (CD45+) cellular compartments of tumor bearing (KPC/Cdh11+/+), tumor bearing Cdh11 deficient (KPC/Cdh11+/-), non-tumor bearing Cdh11 deficient (Cdh11-/+) and wildtype (KP) were performed. We observed changes in the abundance and types of infiltrating immune cells (T-cells, B-cells, myeloid lineage cells) of KPC/Cdh11+/- tumors when compared to tumors harvested from KPC/Cdh11+/+ mice. KPC/Cdh11+/+ pancreata had significantly more myeloid cells while KPC/Cdh11+/- tumors favored an increase in the numbers of infiltrating B- and T- cells. Genes upregulated in infiltrating T-cells specific to KPC/Cdh11+/+ mice include Spp1, Ifi30, Apoe, Ifitm3, Fn1. The increase in B and T cell infiltration was specific to the Cdh11-/+ deficient background, since both pancreata from KPC/Cdh11+/- and Cdh11-/+ mice had elevated levels of infiltration, compared to the KPC group. We also observed a decrease in the number of antigen-presenting cancer associated fibroblasts (apCAFs) in Cdh11-/+ and KPC/Cdh11+/- pancreata, denoted by the lack of CD74+ fibroblasts. Further validation of these findings will help to define the role of Cdh11-/+ in modulating B and T-cell behavior in addition to providing insight into Cdh11-/+ as a therapeutic target for PDAC through altering the tumor microenvironment.

Citation Format: Kelly A. Martin, Aimy Sebastian, Nicholas Hum, Ivana Peran, Stephen Byers, Elizabeth K. Wheeler, Matthew A. Coleman, Gabriela Loots. Loss of Cadherin-11 in PDAC induces altered immune cell infiltration and remodels stromal landscape [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2741.

POS0337 SOUTHEND PRE-TEST PROBABILITY SCORE AND HALO SCORE AS MARKERS FOR DIAGNOSIS AND MONITORING OF GCA: EARLY RESULTS FROM THE PROSPECTIVE HAS-GCA STUDY

Background:

EULAR recommends doppler ultrasound (US) as the first line imaging in patients with Giant Cell Arteritis (GCA) suspect. Traditionally, US non-compressive halo sign has been used for diagnosis but prospective studies on response and disease monitoring are lacking

Objectives:

The HAS GCA study has the objective of prospectively assessing role of US in diagnosis, prognosis and monitoring in newly diagnosed GCA. We report early baseline and up to month 3 data on our current recruitment in a study that has suffered disruption from the pandemic

Methods:

HAS GCA (IRAS#264294) is an ongoing, prospective, multicentre study recruiting from referrals of suspected GCA to fast track clinics. The objective is to recruit 270 patients, including 68 GCA patients. Based on the Southend GCA clinical pre-test probability score (SPTPS)1, patients were stratified in to low, intermediate and high risk categories2. Temporal and axillary US Halo Scores were calculated from the halo thickness and extent in bilateral temporal arteries, parietal and frontal branches and axillary arteries. These individual scores were summed (TA Halo Score x1 plus; AA Halo Score x3) to generate a Total Halo Score (THS)3.

Mann Whitney U test and Fisher’s exact test were used to compare baseline features between GCA and controls. Wilcoxon signed rank test was used to evaluate disease features at baseline and at 3 months in GCA patients. Sensitivity (Sn) and Specificity (Sp) were calculated, where applicable. P value <0.05 is statistically significant

Results:

Ninety-three patients (29 GCA, 64 controls) have been recruited thus far: 18 completed 3-month follow up assessment; 4 were lost to follow up (2 died, 2 withdrew consent due to pandemic). Demographics, clinical features, and US results are shown (Table 1).

Table 1.

Baseline features of GCA patients and controls.

GCA (n=29)Controls (n=64)P-valueAge, median (IQR)75 (71-80)67 (61.25 – 75.0)0.001Female, n (%)15 (42)50 (78)0.01SPTPS category, n (%) Low risk0 (0)31 (48)<0.001 Intermediate risk7 (24)25 (39)0.24 High risk22 (76)8 (13)<0.001Halo score (HS), median (range) Temporal artery HS10 (1-21)1 (0-9)<0.001 Axillary artery HS12 (0-18)6 (0-18)<0.001 Total HS21 (2-38)6 (0-19)<0.001Clinical features, n (%) Temporal headache21 (72)40 (63)0.48 Scalp tenderness17 (59)31 (48)0.38 Jaw claudication19 (66)4 (6)<0.001 PMR symptoms16 (55)6 (9)<0.001 Constitutional symptoms17 (59)18 (28)0.006 Visual disturbance18 (62)38 (59)1 Vision loss7 (24)4 (6)0.03

Among GCA patients, 23 had cranial, 2 large-vessel and 4 mixed phenotypes (cranial plus large vessel) disease.

Jaw claudication (66%) and polymyalgic symptoms (55%) were the dominant features in GCA patients. Median age 75 years in GCA (42% females) and 67 years in controls (78% females). GCA and controls were stratified by SPTPS to Low risk (0% vs 48%; Sn-undefined, Sp-97), Intermediate risk (24% vs 39%; Sn-100, Sp-100) and High risk (76% vs 13%; Sn-95, Sp-88). Optimal SPTPS cut-off point was ≥12 (Sn-93, Sp-86); ≥10 (Sn-100 & Sp-69).

Median THS was 21 in GCA and 6 in controls. Optimal cut-off Halo Score in diagnosis was TAHS ≥5 (Sn-90, Sp-98), AAHS ≥11 (Sn-55, Sp-80), THS ≥18 (Sn-72%, Sp-98%). Among the 18 patients who completed 3-months follow up, median TAHS, AAHS and THS reduced from 10 to 2.5, 12 to 6 and 21 to 10, respectively (Figure 1).

Conclusion:

Along with SPTPS, Halo Score successfully discriminates GCA from non GCA mimics. HS is effective in showing 3-month response and may be a useful marker to monitor GCA disease activity.

References:

[1]Laskou F et al. A probability score to aid the diagnosis of suspected giant cell arteritis. Clin Exp Rheumatol. 2019

[2]Sebastian A et al. Probability-based algorithm using ultrasound and additional tests for suspected GCA in a fast-track clinic. RMD Open. 2020

[3]Sebastian A et al. Halo score (temporal artery, its branches and axillary artery) as a diagnostic, prognostic and disease monitoring tool for Giant Cell Arteritis (GCA). BMC Rheumatol. 2020

Disclosure of Interests:

Alwin Sebastian: None declared, Alessandro Tomelleri: None declared, Abdul Kayani: None declared, Mohammad Tariq: None declared, Diana Prieto-Peña: None declared, Sue Inness: None declared, Jo Jackson: None declared, Kornelis van der Geest Speakers bureau: Roche, Bhaskar Dasgupta Speakers bureau: Roche, GSK, BMS, Sanofi, Abbie, Grant/research support from: Roche

Cadherin 11 Promotes Immunosuppression and Extracellular Matrix Deposition to Support Growth of Pancreatic Tumors and Resistance to Gemcitabine in Mice

BACKGROUND & AIMS

Pancreatic ductal adenocarcinomas (PDACs) are characterized by fibrosis and an abundance of cancer-associated fibroblasts (CAFs). We investigated strategies to disrupt interactions among CAFs, the immune system, and cancer cells, focusing on adhesion molecule CDH11, which has been associated with other fibrotic disorders and is expressed by activated fibroblasts.

METHODS

We compared levels of CDH11 messenger RNA in human pancreatitis and pancreatic cancer tissues and cells with normal pancreas, and measured levels of CDH11 protein in human and mouse pancreatic lesions and normal tissues. We crossed p48-Cre;LSL-Kras^G12D/+;LSL-Trp53^R172H/+ (KPC) mice with CDH11-knockout mice and measured survival times of offspring. Pancreata were collected and analyzed by histology, immunohistochemistry, and (single-cell) RNA sequencing; RNA and proteins were identified by imaging mass cytometry. Some mice were given injections of PD1 antibody or gemcitabine and survival was monitored. Pancreatic cancer cells from KPC mice were subcutaneously injected into Cdh11^+/+ and Cdh11^-/- mice and tumor growth was monitored. Pancreatic cancer cells (mT3) from KPC mice (C57BL/6), were subcutaneously injected into Cdh11^+/+ (C57BL/6J) mice and mice were given injections of antibody against CDH11, gemcitabine, or small molecule inhibitor of CDH11 (SD133) and tumor growth was monitored.

RESULTS

Levels of CDH11 messenger RNA and protein were significantly higher in CAFs than in pancreatic cancer epithelial cells, human or mouse pancreatic cancer cell lines, or immune cells. KPC/Cdh11^+/- and KPC/Cdh11^-/- mice survived significantly longer than KPC/Cdh11^+/+ mice. Markers of stromal activation entirely surrounded pancreatic intraepithelial neoplasias in KPC/Cdh11^+/+ mice and incompletely in KPC/Cdh11^+/- and KPC/Cdh11^-/- mice, whose lesions also contained fewer FOXP3⁺ cells in the tumor center. Compared with pancreatic tumors in KPC/Cdh11^+/+ mice, tumors of KPC/Cdh11^+/- mice had increased markers of antigen processing and presentation; more lymphocytes and associated cytokines; decreased extracellular matrix components; and reductions in markers and cytokines associated with immunosuppression. Administration of the PD1 antibody did not prolong survival of KPC mice with 0, 1, or 2 alleles of Cdh11. Gemcitabine extended survival of KPC/Cdh11^+/- and KPC/Cdh11^-/- mice only or reduced subcutaneous tumor growth in mT3 engrafted Cdh11^+/+ mice when given in combination with the CDH11 antibody. A small molecule inhibitor of CDH11 reduced growth of pre-established mT3 subcutaneous tumors only if T and B cells were present in mice.

CONCLUSIONS

Knockout or inhibition of CDH11, which is expressed by CAFs in the pancreatic tumor stroma, reduces growth of pancreatic tumors, increases their response to gemcitabine, and significantly extends survival of mice. CDH11 promotes immunosuppression and extracellular matrix deposition, and might be developed as a therapeutic target for pancreatic cancer.

Abstract PO065: Single cell transcriptomics of triple negative breast cancer allografts following chemotherapy treatment reveals increased T cell abundance in doxorubicin-sensitive tumors

The contribution of stromal cells on drug response in primary tumors remains unclear. To determine how individual cells within the stroma of triple negative breast cancer (TNBC) allografts respond to chemotherapy, we used single cell sequencing to profile cells present in murine tumors with or without exposure to doxorubicin. Doxorubicin is a chemotherapeutic agent commonly used to treat TNBC by inhibiting cancer cell proliferation through intercalation of DNA and preventing topoisomerase II activity. In this study, murine TNBC 4T1 cell line was utilized to generate allograft tumors in immunocompetent BALB/c mice. Syngeneic 4T1 tumors exhibit a range of responsiveness to doxorubicin treatment. Tumor growth rates were monitored throughout the chemotherapeutic regiment then stratified into sensitive or resistant response. Cellular composition and behavior were then analyzed via single cell RNA sequencing (scRNA-seq) and flow cytometry 8 days post-doxorubicin chemotherapeutic administration mimicking clinical treatment. ScRNA-seq revealed decreases in tumor infiltrating lymphocytes after doxorubicin exposure. Furthermore, an increase in T cell abundance was discovered in tumors sensitive to doxorubicin treatment. This finding was further supported by flow cytometric analysis showing a tumor specific increase in all, CD4+, and CD8+ T cell populations relative to resistant tumors. Additionally, T-cell differentiation, exhaustion, and activation states were further examined from scRNA-seq data providing insights into functional properties of the tumor residing T cell populations undergoing chemotherapeutic treatment. Future work will focus on analyzing prognostic value of specific T-cell populations in disease regression following doxorubicin treatment. This study received funding from LLNL LDRD grant 19-SI-003. This work was conducted under the auspices of the USDOE by LLNL (DE-AC52-07NA27344).

Citation Format: Nicholas R. Hum, Aimy Sebastian, Sean F. Gilmore, David M. Gravano, Naiomy D. Rios-Arce, Kelly A. Martin, Elizabeth K. Wheeler, Matthew A. Coleman, Gabriela G. Loots. Single cell transcriptomics of triple negative breast cancer allografts following chemotherapy treatment reveals increased T cell abundance in doxorubicin-sensitive tumors [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PO065.

LPS-Induced Inflammation Prior to Injury Exacerbates the Development of Post-Traumatic Osteoarthritis in Mice

Osteoarthritis (OA) is a debilitating and painful disease characterized by the progressive loss of articular cartilage. Post-traumatic osteoarthritis (PTOA) is an injury-induced type of OA that persists in an asymptomatic phase for years before it becomes diagnosed in ~50% of injured individuals. Although PTOA is not classified as an inflammatory disease, it has been suggested that inflammation could be a major driver of PTOA development. Here we examined whether a state of systemic inflammation induced by lipopolysaccharide (LPS) administration 5-days before injury would modulate PTOA outcomes. RNA-seq analysis at 1-day post-injury followed by micro-computed tomography (μCT) and histology characterization at 6 weeks post-injury revealed that LPS administration causes more severe PTOA phenotypes. These phenotypes included significantly higher loss of cartilage and subchondral bone volume. Gene expression analysis showed that LPS alone induced a large cohort of inflammatory genes previously shown to be elevated in synovial M1 macrophages of rheumatoid arthritis (RA) patients, suggesting that systemic LPS produces synovitis. This synovitis was sufficient to promote PTOA in MRL/MpJ mice, a strain previously shown to be resistant to PTOA. The synovium of LPS-treated injured joints displayed an increase in cellularity, and immunohistological examination confirmed that this increase was in part attributable to an elevation in type 1 macrophages. LPS induced the expression of Tlr7 and Tlr8 in both injured and uninjured joints, genes known to be elevated in RA. We conclude that inflammation before injury is an important risk factor for the development of PTOA and that correlating patient serum endotoxin levels or their state of systemic inflammation with PTOA progression may help develop new, effective treatments to lower the rate of PTOA in injured individuals. © 2020 The Authors. Journal of Bone and Mineral Research published by American Society for Bone and Mineral Research.

Antibiotic Treatment Prior to Injury Improves Post-Traumatic Osteoarthritis Outcomes in Mice

Osteoarthritis (OA) is a painful and debilitating disease characterized by the chronic and progressive degradation of articular cartilage. Post-traumatic OA (PTOA) is a secondary form of OA that develops in ~50% of cases of severe articular injury. Inflammation and re-occurring injury have been implicated as contributing to the progression of PTOA after the initial injury. However, there is very little known about external factors prior to injury that could affect the risk of PTOA development. To examine how the gut microbiome affects PTOA development we used a chronic antibiotic treatment regimen starting at weaning for six weeks prior to ACL rupture, in mice. A six-weeks post-injury histological examination showed more robust cartilage staining on the antibiotic (AB)-treated mice than the untreated controls (VEH), suggesting slower disease progression in AB cohorts. Injured joints also showed an increase in the presence of anti-inflammatory M2 macrophages in the AB group. Molecularly, the phenotype correlated with a significantly lower expression of inflammatory genes Tlr5, Ccl8, Cxcl13, and Foxo6 in the injured joints of AB-treated animals. Our results indicate that a reduced state of inflammation at the time of injury and a lower expression of Wnt signaling modulatory protein, Rspo1, caused by AB treatment can slow down or improve PTOA outcomes.

Abstract 2757: Analysis of stromal myofibroblasts identifies secreted proteins that promote pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most incurable types of cancer. Cancer that develops in the acinar cells of the pancreas is typically not diagnosed until later stages, such as stage 3 or 4. As such, this form of cancer is particularly lethal with only 9% of patients reaching 5-year survival. PDAC is known to have a particularly dense extracellular matrix composed of fibroblasts, which have been previously shown to play an important role in promoting resistance to drug therapy. Characterization of the stromal networks involved in PDAC tumor development as well as protein markers of fibroblast subpopulations within the tumor stroma are critical to developing new fibroblast-targeted therapeutic approaches as well as understanding key signaling molecules that ultimately promote tumor progression and drug resistance. Single-cell RNA sequencing (scRNAseq) was utilized to analyze cancer-associated fibroblasts (CAFs) from KPC mouse-derived, MT3 subcutaneous murine allografts along with two fibroblast lines derived from human PDAC tumors: CRC-811 and IA-1340. Single cell gene expression profiling and subsequent analysis of MT3-derived CAFs resulted in the identification of three CAF subpopulations including a myofibroblast subpopulation that expressed high levels of smooth muscle actin (Acta2), which was also observed in both human samples. Fibroblast subpopulations enriched in Acta2 expression, expressed high levels of Wnt5a along with several other secreted factors including Tgfb1, Tgfb2 and Ctgf. Wnt5a is a secreted protein that activates non-canonical Wnt signaling pathways and is known to regulate normal developmental processes, including proliferation, differentiation, migration, adhesion and polarity. However Wnt5a is not natively expressed in MT3 cancer cells derived from syngeneic tumors, but potentially in the stroma. We hypothesize it is exclusively derived from fibroblasts. Previously it has been shown that Wnt5a inhibition suppressed gastric cancer metastasis, therefore further validation of the role of myofibroblast-derived Wnt5a on PDAC disease progression is warranted. This study received funding by LDRD 19-SI-003. This work was conducted under the auspices of the USDOE by LLNL (DE-AC52-07NA27344). IM Release Number: LLNL-ABS-798442.

Citation Format: Kelly A. Martin, Aimy Sebastian, Nicholas R. Hum, Stephen Byers, Elizabeth K. Wheeler, Matthew A. Coleman, Gabriela G. Loots. Analysis of stromal myofibroblasts identifies secreted proteins that promote pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2757.

Functional and transcriptional characterization of complex neuronal co-cultures

Brain-on-a-chip systems are designed to simulate brain activity using traditional in vitro cell culture on an engineered platform. It is a noninvasive tool to screen new drugs, evaluate toxicants, and elucidate disease mechanisms. However, successful recapitulation of brain function on these systems is dependent on the complexity of the cell culture. In this study, we increased cellular complexity of traditional (simple) neuronal cultures by co-culturing with astrocytes and oligodendrocyte precursor cells (complex culture). We evaluated and compared neuronal activity (e.g., network formation and maturation), cellular composition in long-term culture, and the transcriptome of the two cultures. Compared to simple cultures, neurons from complex co-cultures exhibited earlier synapse and network development and maturation, which was supported by localized synaptophysin expression, up-regulation of genes involved in mature neuronal processes, and synchronized neural network activity. Also, mature oligodendrocytes and reactive astrocytes were only detected in complex cultures upon transcriptomic analysis of age-matched cultures. Functionally, the GABA antagonist bicuculline had a greater influence on bursting activity in complex versus simple cultures. Collectively, the cellular complexity of brain-on-a-chip systems intrinsically develops cell type-specific phenotypes relevant to the brain while accelerating the maturation of neuronal networks, important features underdeveloped in traditional cultures.

SAT0249 A PROBABILITY-BASED DIAGNOSTIC ALGORITHM FOR SUSPECTED GCA

Background:

Clinical presentation of GCA is protean. It is vital to make a secure diagnosis, exclude mimics urgently and avoid inappropriate steroids to minimise side effects. Fast track GCA clinics (FTC) provide rapid specialist assessment with temporal and axillary US (1). EULAR recommendations support US as first-choice test. A pre-test probability score (PTPS) stratifies patients to low (LC), intermediate (IC) and high-risk (HC) categories.

Objectives:

To validate a diagnostic GCA algorithm based on stratification by PTPS, with sequential US and additional tests (AT), if necessary

Methods:

For the algorithm (Figure) retrospective data was extracted from case records of cases seen in 2019. PTPS overall showed median (Q2) score of 9,75thpercentile (Q3) score 12. Based on this and reported cut-off 9.5 (2) we classified LC as PTPS <9, IC 9-12 and HC >12 (Graph). GCA diagnosis was by modified GiACTA including US (Halo), CRP > 5 mg/L and AT if necessary. The algorithm performance was assessed overall and in individual categories.

Results:

Of 187 consecutive cases, 13 were excluded for incomplete data (tertiary referrals). In remaining 174, GCA confirmed 33%, mean age 72.4 years, 69% females,45% LC, 35% IC, and 20% HC. 130 (75%) had US whereas 44 did not (41 LC, 3 IC) (Figure)

In HC, 25/31 (81%) were US +ve, 19 treated as GCA without AT, 6 with AT (Table 2). Of 6 US -ve 3 had GCA confirmed by AT (PET-CT 2, TAB 1). US in HC showed sensitivity 89%, specificity 75%, accuracy 87%, GCA prevalence 87%, mean CRP 65.52 (SEM+/- 8.67).

Table 1.

US performance with PTPS

Category(n)USGCA, nNon-GCA, nSensitivity (%)Specificity (%)PPV (%)NPV(%)Prevalence (%)Accuracy(%)HC (31)+24124/27(89)3/4(75)24/25(96)3/6(50)27/31(87)(24 + 3)/31(87)-33IC (65)+30030/30(100)35/35(100)30/30(100)35/35(100)30/65(46)(30 + 35)/65(100)-035LC (78)+010/0 (undefined)77/78(99)0/1(0)77/77(100)0/78(0)(0 + 77)/78(99)-077Total (174)+54254/57(95)115/117(98)54/56(96)115/118(97)57/174(33)(54 + 115)/174(97)-3115

Abbreviations: GCA, Giant cell arteritis; NPV, Negative predictive value; PPV, Positive predictive value; US, Ultrasound

Table 2.

US, AT & confirmed diagnosis

CategoryUltrasoundNo of ATType of ATFinal Diagnosis+veNot done-veLC(78)1393871x TAB (-), CTB (-)Fibromyalgia1x TAB (-), MRA (-), MR neck (+)Tongue cancer1x CTA (+)Stroke1x CTCAP (-)IA1x PET (-)PMR1xTAB (-)NA AION1x PET (-)CVAIC(65)30332155x TAB (-), 2x PET (-)Not GCA2x TAB (+), 6x PET (+)GCAHC(31)2506101x PET (-)URTI1x TAB (-)NAAION2x PET (+)1x TAB (+)1x CTA (+)1x MRA (+)GCA1x PET (-)2x CTA (-)1x CTCAP (-)

Abbreviations: AT, Additional test; CTA, Computed tomography angiogram; CTB, Computed tomography of brain; CTCAP, Computed tomography of chest, abdomen and pelvis; GCA, Giant cell arteritis; IA, Inflammatory arthritis; MRA, Magnetic resonant angiogram; NA AION, Non arteritic anterior ischemic optic neuritis; PET, Position emission tomography; TAB, Temporal artery biopsy; URTI, Upper respiratory tract infection

In LC, 38 (49%) were US - ve, of whom 5 had AT. US not done on 39 (50%) for either PTPS very low or urgent alternative diagnosis. 1 went on to AT. 1 was US positive and had GCA excluded with AT. US in LC showed specificity 99%, sensitivity 0/0 (undefined), accuracy 99%, GCA prevalence 0%, mean CRP 21.79 (SEM+/- 3.80)

In IC, 30/65 (46%) were US +ve 8 had AT (all GCA confirmed) while on treatment. 32 (49%) US negative where 7 had AT (all GCA excluded). 3 did not have US. Sensitivity, specificity, accuracy of US was all 100%, GCA prevalence 46%, mean CRP 39.05 (SEM+/- 5.04)

US test performance overall sensitivity 95%, specificity 98%, accuracy 97%

Conclusion:

PTPS successfully stratifies GCA, excludes mimics and enhances US performance. The algorithm interprets correctly US findings and choice of AT.

References:

[1]Patil et al Clin Exp Rheumatol 2015;33(Suppl 89): S103–6.

[2]Laskou et al. Clin Exp Rheumatol. 2019 Feb 15

Disclosure of Interests:

Alwin Sebastian: None declared, Abdul Kayani: None declared, Chavini Ranasinghe: None declared, Bhaskar Dasgupta Grant/research support from: Roche, Consultant of: Roche, Sanofi, GSK, BMS, AbbVie, Speakers bureau: Roche

Single-Cell Transcriptomic Analysis of Tumor-Derived Fibroblasts and Normal Tissue-Resident Fibroblasts Reveals Fibroblast Heterogeneity in Breast Cancer

Cancer-associated fibroblasts (CAFs) are a prominent stromal cell type in solid tumors and molecules secreted by CAFs play an important role in tumor progression and metastasis. CAFs coexist as heterogeneous populations with potentially different biological functions. Although CAFs are a major component of the breast cancer stroma, molecular and phenotypic heterogeneity of CAFs in breast cancer is poorly understood. In this study, we investigated CAF heterogeneity in triple-negative breast cancer (TNBC) using a syngeneic mouse model, BALB/c-derived 4T1 mammary tumors. Using single-cell RNA sequencing (scRNA-seq), we identified six CAF subpopulations in 4T1 tumors including: 1) myofibroblastic CAFs, enriched for α-smooth muscle actin and several other contractile proteins; 2) ‘inflammatory’ CAFs with elevated expression of inflammatory cytokines; and 3) a CAF subpopulation expressing major histocompatibility complex (MHC) class II proteins that are generally expressed in antigen-presenting cells. Comparison of 4T1-derived CAFs to CAFs from pancreatic cancer revealed that these three CAF subpopulations exist in both tumor types. Interestingly, cells with inflammatory and MHC class II-expressing CAF profiles were also detected in normal breast/pancreas tissue, suggesting that these phenotypes are not tumor microenvironment-induced. This work enhances our understanding of CAF heterogeneity, and specifically targeting these CAF subpopulations could be an effective therapeutic approach for treating highly aggressive TNBCs.

Osteogenic preconditioning in perfusion bioreactors improves vascularization and bone formation by human bone marrow aspirates

Cell-derived extracellular matrix (ECM) provides a niche to promote osteogenic differentiation, cell adhesion, survival, and trophic factor secretion. To determine whether osteogenic preconditioning would improve the bone-forming potential of unfractionated bone marrow aspirate (BMA), we perfused cells on ECM-coated scaffolds to generate naïve and preconditioned constructs, respectively. The composition of cells selected from BMA was distinct on each scaffold. Naïve constructs exhibited robust proangiogenic potential in vitro, while preconditioned scaffolds contained more mesenchymal stem/stromal cells (MSCs) and endothelial cells (ECs) and exhibited an osteogenic phenotype. Upon implantation into an orthotopic calvarial defect, BMA-derived ECs were present in vessels in preconditioned implants, resulting in robust perfusion and greater vessel density over the first 14 days compared to naïve implants. After 10 weeks, human ECs and differentiated MSCs were detected in de novo tissues derived from naïve and preconditioned scaffolds. These results demonstrate that bioreactor-based preconditioning augments the bone-forming potential of BMA.

Global Gene Expression Analysis Identifies Age-Related Differences in Knee Joint Transcriptome during the Development of Post-Traumatic Osteoarthritis in Mice

Aging and injury are two major risk factors for osteoarthritis (OA). Yet, very little is known about how aging and injury interact and contribute to OA pathogenesis. In the present study, we examined age- and injury-related molecular changes in mouse knee joints that could contribute to OA. Using RNA-seq, first we profiled the knee joint transcriptome of 10-week-old, 62-week-old, and 95-week-old mice and found that the expression of several inflammatory-response related genes increased as a result of aging, whereas the expression of several genes involved in cartilage metabolism decreased with age. To determine how aging impacts post-traumatic arthritis (PTOA) development, the right knee joints of 10-week-old and 62-week-old mice were injured using a non-invasive tibial compression injury model and injury-induced structural and molecular changes were assessed. At six-week post-injury, 62-week-old mice displayed significantly more cartilage degeneration and osteophyte formation compared with young mice. Although both age groups elicited similar transcriptional responses to injury, 62-week-old mice had higher activation of inflammatory cytokines than 10-week-old mice, whereas cartilage/bone metabolism genes had higher expression in 10-week-old mice, suggesting that the differential expression of these genes might contribute to the differences in PTOA severity observed between these age groups.

Expression of a Degradation-Resistant β-Catenin Mutant in Osteocytes Protects the Skeleton From Mechanodeprivation-Induced Bone Wasting

Mechanical stimulation is a key regulator of bone mass, maintenance, and turnover. Wnt signaling is a key regulator of mechanotransduction in bone, but the role of β-catenin-an intracellular signaling node in the canonical Wnt pathway-in disuse mechanotransduction is not defined. Using the β-catenin exon 3 flox (constitutively active [CA]) mouse model, in conjunction with a tamoxifen-inducible, osteocyte-selective Cre driver, we evaluated the effects of degradation-resistant β-catenin on bone properties during disuse. We hypothesized that if β-catenin plays an important role in Wnt-mediated osteoprotection, then artificial stabilization of β-catenin in osteocytes would protect the limbs from disuse-induced bone wasting. Two disuse models were tested: tail suspension, which models fluid shift, and botulinum-toxin (botox)-induced muscle paralysis, which models loss of muscle force. Tail suspension was associated with a significant loss of tibial bone mass and density, reduced architectural properties, and decreased bone formation indices in uninduced (control) mice, as assessed by dual-energy X-ray absorptiometry (DXA), micro-computed tomography (µCT), and histomorphometry. Activation of the βcatCA allele in tail-suspended mice resulted in little to no change in those properties; ie, these mice were protected from bone loss. Similar protective effects were observed among botox-treated mice when the βcatCA was activated. RNAseq analysis of altered gene regulation in tail-suspended mice yielded 35 genes, including Wnt11, Gli1, Nell1, Gdf5, and Pgf, which were significantly differentially regulated between tail-suspended β-catenin stabilized mice and tail-suspended nonstabilized mice. Our findings indicate that selectively targeting/blocking of β-catenin degradation in bone cells could have therapeutic implications in mechanically induced bone disease. © 2019 American Society for Bone and Mineral Research.

The Sustained Induction of c-MYC Drives Nab-Paclitaxel Resistance in Primary Pancreatic Ductal Carcinoma Cells

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive disease with limited and, very often, ineffective medical and surgical therapeutic options. The treatment of patients with advanced unresectable PDAC is restricted to systemic chemotherapy, a therapeutic intervention to which most eventually develop resistance. Recently, nab-paclitaxel (n-PTX) has been added to the arsenal of first-line therapies, and the combination of gemcitabine and n-PTX has modestly prolonged median overall survival. However, patients almost invariably succumb to the disease, and little is known about the mechanisms underlying n-PTX resistance. Using the conditionally reprogrammed (CR) cell approach, we established and verified continuously growing cell cultures from treatment-naïve patients with PDAC. To study the mechanisms of primary drug resistance, nab-paclitaxel-resistant (n-PTX-R) cells were generated from primary cultures and drug resistance was verified in vivo, both in zebrafish and in athymic nude mouse xenograft models. Molecular analyses identified the sustained induction of c-MYC in the n-PTX-R cells. Depletion of c-MYC restored n-PTX sensitivity, as did treatment with either the MEK inhibitor, trametinib, or a small-molecule activator of protein phosphatase 2a. IMPLICATIONS: The strategies we have devised, including the patient-derived primary cells and the unique, drug-resistant isogenic cells, are rapid and easily applied in vitro and in vivo platforms to better understand the mechanisms of drug resistance and for defining effective therapeutic options on a patient by patient basis.

Abstract 130: Characterization of the tumor microenvironment using single cell transcriptomics of triple negative breast cancer allografts treated with doxorubicin

It is currently unclear how stromal components affect drug response and the emergence of drug resistance, in primary tumors. To determine how individual cells within the stroma of triple negative breast cancer (TNBC) allografts respond to chemotherapy, we used single cell sequencing to profile individual cells present in murine tumors with or without exposure to doxorubicin (Dox). Dox is a common chemotherapeutic agent used to treat breast cancer which inhibits breast cancer proliferation by intercalating into DNA and preventing topoisomerase II activity. Several autonomous processes have been implicated in the development of chemoresistance yet the impact of stromal and immune cells on tumor progression is still poorly understood. In this study, TNBC 4T1 cell line were utilized to generate murine allograft tumors in immunocompetent BALB/c mice. Tumor composition was analyzed via single cell RNA sequencing after 3 and 7 days of doxorubicin chemotherapeutic regiment mimicking clinical treatment.

Using Cell Ranger single cell software suite and Seurat R toolkit, single cell transcriptomic analysis identified the cellular composition of tumors through expression of cell-type specific genes. Stromal cell types such as endothelial, fibroblast and epithelial cells were assessed and quantified in the tumor microenvironment. Immune cell types including neutrophils, monocytes, macrophages, T-cells and B-cells were also identified in the stroma and the responses to doxorubicin treatment was determined based on the gene expression changes. In this study, cancer-associated fibroblasts and non-canonical tumor associated macrophage subpopulations are of particular interest. As expected, we found both qualitative and quantitative changes in specific subpopulations of stromal cells in response to Dox exposure.

Identification of stromal and immune cell sub-types could also lead to improved diagnostic capabilities and tumor susceptibilities. Future studies modulating non-cancerous cells in the tumor microenvironment may increase efficacy of chemotherapeutics. Further elucidating the specific cellular subpopulations within the tumor microenvironment that shift in response to drug exposure may provide new therapeutic avenues. Understanding changes in cell populations within the drug exposed tumor microenvironment can aid in future drug development to specifically target cells least sensitive to chemotherapy exposure.

This study received funding from LLNL LDRD grant 19-SI-003. This work was conducted under the auspices of the USDOE by LLNL (DE-AC52-07NA27344).

Citation Format: Nicholas Hum, Aimy Sebastian, Sean Gilmore, Elizabeth K. Wheeler, Matthew A. Coleman, Gabriela G. Loots. Characterization of the tumor microenvironment using single cell transcriptomics of triple negative breast cancer allografts treated with doxorubicin [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 130.

Abstract 5157: Comparison of exosomes shed by breast cancer cell lines with varying metastatic potential

Exosomes are endosomal secreted vesicles containing a variety of genetic and non-genetic material that can be transferred between cells (DNA, RNA, protein, lipid, etc.). Cancer derived exosomes have been implicated in a wide range of cancer mechanisms such as promotion of tumor growth, tumor angiogenesis, immune evasion, drug resistance, and metastasis. In addition to functional significance, cancer exosomes may possess novel biomarkers with potential uses for non-invasive liquid biopsies for cancer detection and monitoring of disease progression. Here we examined differences that may exist in extracellular vesicles or exosomes (EVs) shed by cancer cell lines with various metastatic potential (MDA-MB-231, highly metastatic; MCF-7, weakly metastatic; MCF-10a, normal breast epithelial cells). Morphological analysis of EVs was performed using fluorescent Nanosight Tracking Analysis and revealed decreased mean diameter of EVs derived from MCF-7 cells compared to the other two cell lines, there was also increased exosome particle yield in this cell line. Small RNAs from EVs cargo were also analyzed via sequencing (exoRNA-Seq). The majority of sequenced RNA aligned to coding regions of the human genome (~60%) across all cell lines. Non-coding RNA classification also showed little variability across cell lines examined regardless of metastatic potential, with ~38% of RNA reads corresponding to non-coding RNAs. Pairwise comparison of these cell lines demonstrated that each line packaged unique cargos into their shed exosomes. The non-coding regions corresponded to a variety of small RNAs (miRNA, snoRNA, snRNA, miscRNA, rRNA) but included other RNA features such as pseudogenes and antisense RNAs. We found 304 genes significantly up-regulated and 150 genes significantly down-regulated when comparing metastatic cancer exosomes (MCF-7 and MDA-MB-231) to normal, non-tumorigenic exosomes (MCF-10A). Among examined microRNAs we found several miRNAs associated with metastatic behavior that have previously been implicated in cancer biology, which will be prioritized for validation. Also, 21 RNAs were upregulated at high levels in exosomes shed by metastatic cells, and their expression level was directly proportional with the metastatic character, suggesting that these RNAs may be tested for their potential as biomarkers. Future research will expand upon these newly identified genetic signatures of metastatic exosomal cargo and further validate their influence in driving metastasis.

This study received funding from DOD grant BC151687. This work was conducted under the auspices of the USDOE by LLNL (DE-AC52-07NA27344). IM number: LLNL-POST-758941

Citation Format: Kelly A. Martin, Nicholas R. Hum, Aimy Sebastian, Gabriela G. Loots. Comparison of exosomes shed by breast cancer cell lines with varying metastatic potential [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5157.

Abstract 37: RNA-seq comparisons of in vitro and in vivo cancer model platforms: Monolayer, spheroids, immunodeficient, and syngeneic mouse model

Preclinical cancer models have been vital contributors in minimizing this burden as well as understanding basic cancer cell biology, however conventional and modern cancer models do not accurately or reliably recapitulate the complex in vivo tumor environment. Clinical significance of discoveries made using in vitromodels requires an understanding of the limitations imparted from cancer cells in a non-native environment. An ideal pre-clinical cancer platform that mimicks in vivo molecular phenotypes is essential for achieving effective drug screening and personalized treatments. This study aims to elucidate biological processes deficient in conventional in vitro methods from in vivo grown allograft cancer cells via transcriptome analysis.

The effects of culturing conditions on cancer cells were analyzed via whole transcriptome RNA sequencing on a mouse mammary carcinoma (4T1) cell line grown in multiple culture conditions: 2D (monolayer) or 3D (spheroid) constructs under static or dynamic flow in addition to 4T1 cells isolated from subcutaneous or orthotopically grown tumors into the mammary fat pad of immune-competent, BALB/c mice.

Comparative analysis of whole transcriptomic profiles of 4T1 cells in differing culturing conditions reveals distinct biological processes fostered by their environment. Monolayer culture shows enrichment in gene ontologies promoting proliferation, cell cycle progression, and protein synthesis. Compared to monolayer culture all 3-dimensional culturing methods encouraged the expression of proteins known to be critical to tumor progression such as extracellular matrix remodeling, adhesion, and differentiation. Furthermore, spheroid culture introduced heterogeneity as evidenced by upregulation of hypoxic induced genes and regulation of multicellular organism development processes. As expected, 4T1 cells expanded in vivo upregulated genes associated with processes difficult to recapitulate in vitro such as cell migration, inflammatory response, and angiogenesis.

3D culturing methods are able to recapitulate aspects of tumor heterogeneity yet fail to incorporate the complex heterogeneous cell composition and transient fluxes in nutrients and drugs found in vivo. Findings from this study demonstrate the behavioral and transcriptional alterations imparted from environmental factors. Additionally, clinically relevant in vitro testing can be improved by the incorporation of factors found in the native tumor microenvironment to existing 3D culturing approaches.

This study received funding from LLNL LDRD grant 19-SI-003. This work was conducted under the auspices of the USDOE by LLNL (DE-AC52-07NA27344).

Citation Format: Nicholas Hum, Aimy Sebastian, Wei He, Monica L. Moya, William F. Hynes, Jonathan J. Adorno, Aubree Hinckley, Elizabeth K. Wheeler, Matthew A. Coleman, Gabriela G. Loots. RNA-seq comparisons of in vitro and in vivo cancer model platforms: Monolayer, spheroids, immunodeficient, and syngeneic mouse model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 37.

Innate immune responses to Rift Valley fever virus in the brain

Rift Valley Fever Virus (RVFV) is a category A biodefense pathogen due to the potential for intentional spread by aerosol and the lack of any licensed vaccine or antiviral therapeutics. Despite the brain being a major target of viral replication and tissue damage following aerosol infection, little is known about innate immune responses to RVFV in the brain. Thus, we are investigating the responses of resident innate immune cells of the brain to RVFV infection. Microglia and astrocytes mount a robust response to RVFV infection that is dependent upon MAVS and independent of TLR3 and TLR7. MAVS KO mice have significantly higher viral titers in the brain following intranasal infection, but surprisingly many markers of immune activity were similarly upregulated in the brains of WT and KO mice, including infiltration of CD45+ cells, upregulation of inflammatory genes, and cytokine expression. Indeed, many inflammatory and cytokine genes were upregulated more significantly in infected KO brains than in WT. This is in contrast to the in vitro response of microglia and astrocytes, where MAVS KO cells were virtually unresponsive to RVFV infection. RNA-seq analysis of infected brain tissue revealed that key signal transduction pathways are not activated in MAVS KO animals. These results are an important step towards understanding the precise molecular pathways responsible for controlling RVFV infection in the brain, and will be critical to informing the development of vaccines and antiviral therapeutics that are successful in preventing encephalitis caused by RVFV.

Comparative Transcriptomics Identifies Novel Genes and Pathways Involved in Post-Traumatic Osteoarthritis Development and Progression

Anterior cruciate ligament (ACL) injuries often result in post-traumatic osteoarthritis (PTOA). To better understand the molecular mechanisms behind PTOA development following ACL injury, we profiled ACL injury-induced transcriptional changes in knee joints of three mouse strains with varying susceptibility to OA: STR/ort (highly susceptible), C57BL/6J (moderately susceptible) and super-healer MRL/MpJ (not susceptible). Right knee joints of the mice were injured using a non-invasive tibial compression injury model and global gene expression was quantified before and at 1-day, 1-week, and 2-weeks post-injury using RNA-seq. Following injury, injured and uninjured joints of STR/ort and injured C57BL/6J joints displayed significant cartilage degeneration while MRL/MpJ had little cartilage damage. Gene expression analysis suggested that prolonged inflammation and elevated catabolic activity in STR/ort injured joints, compared to the other two strains may be responsible for the severe PTOA phenotype observed in this strain. MRL/MpJ had the lowest expression values for several inflammatory cytokines and catabolic enzymes activated in response to ACL injury. Furthermore, we identified several genes highly expressed in MRL/MpJ compared to the other two strains including B4galnt2 and Tpsab1 which may contribute to enhanced healing in the MRL/MpJ. Overall, this study has increased our knowledge of early molecular changes associated with PTOA development.

Abstract 2528: Determining gene expression variability between in vitro and in vivo cancer models: Monolayer, spheroids, and mouse allografts

An ideal pre-clinical environment that recapitulates in vivo growth conditions ex vivo is an essential pre-requisite for effective drug screening. Conventional monolayer culturing of cancer cells as a pre-clinical model have repeatedly failed to recapitulate responses seen clinically. While 3D culturing methods are able to generate some level of tumor heterogeneity including hypoxic core, cell-cell interactions, gradients of drug penetration, as well as cancer stem cell differentiation, these culturing methods fail to incorporate the complex heterogenous cell composition and transient fluxes in nutrients or drugs.

To investigate the effects of culturing conditions on gene expression of cancer cells, RNA sequencing was performed on a mouse mammary carcinoma (4T1) cell line grown in a variety of culture conditions: 2D (monolayer) or 3D (spheroid). Additionally, gene expression analysis was performed on tumors derived from 4T1 cells injected subcutaneously (SQ) into the murine flank or orthotopically (OT) into the mammary fat pad of BALB/c mice.

Pairwise analysis of RNA sequencing data identified 235 down- and 1029 up- regulated genes differentially expressed between the 2D and 3D culture methods. Differential expression identified genes involved in cell migration, extracellular matrix organization, cell adhesion, angiogenesis, hypoxic response, cell differentiation, as well as key cancer related pathways including TNF, Jak-STAT, and PI3K-AKt primarily upregulated in 3D culture. Similar differential expression was found for genes encoding extracellular matrix proteins, which may be reflective of the 3D environment. Both in vivo allograft models produced highly similar gene expression profiles with only 31 up- and 20 down- regulated genes differentially expressed between OT and SQ tumors. Down-regulated genes were enriched in transcriptional regulatory gene networks and up-regulated genes were enriched for signaling/secreted proteins. The gene expression profiles of in vivo tumors were significantly different when compared to the 2D (973 down regulated, 1971 upregulated genes); and 99 of these transcripts were only expressed in in vivo tumors, highlighting the increased heterogeneity of cell composition found in allografts.

3D culturing of cancer cells upregulates pathways known to be critical to tumor progression including genes known to be essential for adhesion, differentiation, and ECM remodeling however the gene expression profile of spheroids is significantly different than that of cancer cells expanded in vivo. Future culturing methods incorporating immune cells, cancer supporting cells such as fibroblasts and other stromal components are more likely to improve the phenotype of 3D cultured tumor cells.

This study received funding from LLNL LDRD grant 17-ERD-121. This work was conducted under the auspices of the USDOE by LLNL (DE-AC52-07NA27344).

Citation Format: Nicholas R. Hum, Wei He, Aimy Sebastian, Elizabeth K. Wheeler, Matthew A. Coleman, Gabriela G. Loots. Determining gene expression variability between in vitro and in vivo cancer models: Monolayer, spheroids, and mouse allografts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2528.

Abstract 908: Overexpression of nicotinamide N-methyltransferase confers gemcitabine resistance in bladder cancer

Bladder cancer is among the top ten most common cancers diagnosed, with about ~380,000 new cases and ~150,000 deaths per year reported worldwide. Platinum-based chemotherapy in combination with gemcitabine, a nucleoside analog, is a widely used treatment option for advanced bladder cancer. It has been shown that only ~50% of the patients with advanced bladder cancer respond to platinum-based therapy. Cancer cells often become non-responsive to therapy that once proved efficacious and are now drug resistant. Drug resistance represents a significant, ongoing challenge in eradicating cancer.

We have employed a patient-derived bladder cancer xenograft (PDX) platform to further investigate the molecular mechanisms that contribute to gemcitabine-induced drug resistance in advanced bladder cancer. Transcriptome profiling of passage 4 bladder cancer xenograft tumors from 2 gemcitabine sensitive PDX lines (BL0440 & BL0293) was performed using RNA sequencing (RNAseq) analysis, before and after a 21-day cisplatin/gemcitabine drug treatment regimen. Key regulatory pathways and genes contributing to drug resistant bladder cancer have been identified and validated by overexpression in a 5637 bladder cancer cell line.

RNA sequencing data has indicated significant differences between the transcriptional profiles of drug-sensitive and drug-resistant tumors. PDXs retained morphology and shared 92-97% of genetic alterations of parental cancer cells. We identified 106 genes &gt;1.5 fold up-regulated and 45 genes &gt;1.5 fold down-regulated in the drug resistant tumors compared to their drug sensitive counterparts. Of the genes that were significantly upregulated, two methyltransferase enzymes were further validated: Nicotinamide N-methyltransferase (NNMT) and methionine methyltransferase 1A (MAT1A). These genes were found to be contributors to gemcitabine-mediated drug resistance. 5637 cells overexpressing NNMT yielded a 200-fold increase in gemcitabine resistance relative to parental strain. In conclusion, chemoresistance to gemcitabine is associated with differential expression of genes and alteration of downstream signaling pathways. Upregulation of NNMT & MAT1A can potentially be used as novel biomarkers for subpopulations of drug resistant bladder cancer for which improved therapeutics can be developed. Future direction will likely include studies to elucidate exact molecular mechanisms by which cancer cells utilize methyltransferases to no longer respond to gemcitabine therapy.

This work was conducted under the auspices of the USDOE by LLNL (DE-AC52-07NA27344).

Citation Format: Kelly A. Martin, Aimy Sebastian, Nicholas R. Hum, Deepa K. Murugesh, Chong-xian Pan, Ai-Hong Ma, Ralph W. de Vere White, Gabriela G. Loots. Overexpression of nicotinamide N-methyltransferase confers gemcitabine resistance in bladder cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 908.

SOST/Sclerostin Improves Posttraumatic Osteoarthritis and Inhibits MMP2/3 Expression After Injury

Patients with anterior cruciate ligament (ACL) rupture are two times as likely to develop posttraumatic osteoarthritis (PTOA). Annually, there are ∼900,000 knee injuries in the United States, which account for ∼12% of all osteoarthritis (OA) cases. PTOA leads to reduced physical activity, deconditioning of the musculoskeletal system, and in severe cases requires joint replacement to restore function. Therefore, treatments that would prevent cartilage degradation post-injury would provide attractive alternatives to surgery. Sclerostin (Sost), a Wnt antagonist and a potent negative regulator of bone formation, has recently been implicated in regulating chondrocyte function in OA. To determine whether elevated levels of Sost play a protective role in PTOA, we examined the progression of OA using a noninvasive tibial compression overload model in SOST transgenic (SOST^TG ) and knockout (Sost^-/- ) mice. Here we report that SOST^TG mice develop moderate OA and display significantly less advanced PTOA phenotype at 16 weeks post-injury compared with wild-type (WT) controls and Sost^-/- . In addition, SOST^TG built ∼50% and ∼65% less osteophyte volume than WT and Sost^-/- , respectively. Quantification of metalloproteinase (MMP) activity showed that SOST^TG had ∼2-fold less MMP activation than WT or Sost^-/- , and this was supported by a significant reduction in MMP2/3 protein levels, suggesting that elevated levels of SOST inhibit the activity of proteolytic enzymes known to degrade articular cartilage matrix. Furthermore, intra-articular administration of recombinant Sost protein, immediately post-injury, also significantly decreased MMP activity levels relative to PBS-treated controls, and Sost activation in response to injury was TNFα and NF-κB dependent. These results provide in vivo evidence that sclerostin functions as a protective molecule immediately after joint injury to prevent cartilage degradation. © 2018 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals Inc.