Abstract 677: Increasing plexity of imaging mass cytometry for tumor tissue analysis

Imaging Mass Cytometry™ (IMC™) is the leading platform for high-plex tissue imaging. IMC allows for detailed assessment of cell phenotype and function using 40-plus markers simultaneously at subcellular resolution on a single slide. A comprehensive IMC panel containing structural, functional, and immune markers enables us to reveal the complex heterogeneity of tumor tissues as well as the tumor microenvironment (TME). Driven by an increase in the number of antibody markers and the addition of mRNA markers, there is an increasing demand for larger panels. In addition, increasing the number of investigated target markers on a single tissue enriches spatial characterization that may facilitate a more accurate prediction of disease progression and preclinical outcome measures in clinical research projects using tumor biopsies or tissue microarrays (TMAs). Therefore, to increase the plexity of IMC panels, it is essential to expand the number of available metal channels. Here, we demonstrate the incorporation of conjugated antibodies with yttrium (89Y) and indium (115In), two low-mass metals, for IMC application. These metal tags have been previously tested as putative channels for IMC application.

We performed IMC analysis of various tissue types stained with panels of conjugated antibodies including the novel 89Y- and 115In-conjugated antibodies. At least 3 different regions of interest (ROIs) were assessed for each of the investigated tissue types. We compared images for the 89Y- and 115In-conjugated antibodies with the images generated using Maxpar® catalog antibodies of the same clones, with a focus on marker specificity and background signal. Compared with the lanthanide-conjugated catalog antibodies, the 89Y- and 115In-conjugated antibodies showed equivalent specificity and staining quality.

Our results open a new avenue to assign markers to 89Y and 115In, which enables a larger list of potential targets to be investigated in any IMC study. Expanding the number of markers to 40-plus in Imaging Mass Cytometry will improve the imaging results necessary to identify novel cell signatures (phenotype and interactions) in the TME.

Citation Format: Thomas D. Pfister, Shaida Ouladan, Huihui Yao, Daniel Majonis, Christina Loh, Nick Zabinyakov. Increasing plexity of imaging mass cytometry for tumor tissue analysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 677.

Abstract 2250: Immuno-oncology study to profile the tumor microenvironment in multiple human cancers using high-plex imaging mass cytometry

Immune profiling of tumor tissues has become a key tool in understanding the complexity of the tumor microenvironment (TME), for predictive biomarker discovery, and in cancer treatment. The presence of tumor-infiltrating lymphocytes has been associated with benefit from therapy. Furthermore, the TME also contains immunosuppressive elements that can impede immune response. Imaging Mass Cytometry™ (IMC™) enables detailed assessment of cell phenotype and function using 40-plus markers simultaneously at subcellular resolution on a single slide without spectral overlap or background autofluorescence. High-plex IMC has enabled us to evaluate the TME in different cancer histologies including in highly autofluorescent tissue types like lung, hepatocellular carcinoma, and skin melanoma.

The Maxpar® Human Immuno-Oncology IMC Panel Kit (201508) was customized using antibodies from the Standard BioTools™ catalog to create panels for tissue-based immuno-oncology research. Data acquisition was performed using a Hyperion™ Imaging System. To facilitate cell segmentation, an IMC Cell Segmentation Kit (TIS-00001) was applied to enhance cell membrane boundaries. We applied a pixel classification approach and CellProfiler™ for single-cell segmentation. We used histoCAT™ for single-cell analysis to visualize protein expression in various cancer types via PhenoGraph clustering and t-SNE maps.

Our panels were applied to normal and cancer human tissue microarrays (TMAs) to phenotype and analyze cell populations in these tissues. We provide detailed analysis of the TME by classifying activation state of immune cell populations, epithelial-to-mesenchymal transition (EMT) progression, and composition of the extracellular matrix. In-depth single-cell analysis quantitatively evaluated the cellular makeup and immune cell component in the TME of cancer tissues and identified major tumor, immune, and stromal cell phenotypes. This work demonstrates the capability of IMC for quantitative and spatial identification of multiple immune parameters in the TME on a single slide of cancer patient samples (e.g. tumor microarray).

For Research Use Only. Not for use in diagnostic procedures.

Citation Format: Thomas D. Pfister, Liang Lim, Shaida Ouladan, Nick Zabinyakov, Qanber Raza, Christina Loh. Immuno-oncology study to profile the tumor microenvironment in multiple human cancers using high-plex imaging mass cytometry [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2250.

Helminth-induced reprogramming of the stem cell compartment inhibits type 2 immunity

Enteric helminths form intimate physical connections with the intestinal epithelium, yet their ability to directly alter epithelial stem cell fate has not been resolved. Here we demonstrate that infection of mice with the parasite Heligmosomoides polygyrus bakeri (Hpb) reprograms the intestinal epithelium into a fetal-like state marked by the emergence of Clusterin-expressing revival stem cells (revSCs). Organoid-based studies using parasite-derived excretory-secretory products reveal that Hpb-mediated revSC generation occurs independently of host-derived immune signals and inhibits type 2 cytokine-driven differentiation of secretory epithelial lineages that promote their expulsion. Reciprocally, type 2 cytokine signals limit revSC differentiation and, consequently, Hpb fitness, indicating that helminths compete with their host for control of the intestinal stem cell compartment to promote continuation of their life cycle.

Taking a Step Back: Insights into the Mechanisms Regulating Gut Epithelial Dedifferentiation

Despite the environmental constraints imposed upon the intestinal epithelium, this tissue must perform essential functions such as nutrient absorption and hormonal regulation, while also acting as a critical barrier to the outside world. These functions depend on a variety of specialized cell types that are constantly renewed by a rapidly proliferating population of intestinal stem cells (ISCs) residing at the base of the crypts of Lieberkühn. The niche components and signals regulating crypt morphogenesis and maintenance of homeostatic ISCs have been intensely studied over the last decades. Increasingly, however, researchers are turning their attention to unraveling the mechanisms driving gut epithelial regeneration due to physical damage or infection. It is now well established that injury to the gut barrier triggers major cell fate changes, demonstrating the highly plastic nature of the gut epithelium. In particular, lineage tracing and transcriptional profiling experiments have uncovered several injury-induced stem-cell populations and molecular markers of the regenerative state. Despite the progress achieved in recent years, several questions remain unresolved, particularly regarding the mechanisms driving dedifferentiation of the gut epithelium. In this review, we summarize the latest studies, primarily from murine models, that define the regenerative processes governing the gut epithelium and discuss areas that will require more in-depth investigation.

Angiopoietin1 Deficiency in Hepatocytes Affects the Growth of Colorectal Cancer Liver Metastases (CRCLM)

Colorectal cancer liver metastases (CRCLM) that receive their blood supply via vessel co-option are associated with a poor response to anti-angiogenic therapy. Angiopoietins (Ang1 and Ang2) with their Tyrosine-protein kinase receptor (Tie2) have been shown to support vessel co-option. We demonstrate significantly higher expression of Ang1 in hepatocytes adjacent to the tumor region of human chemonaïve and treated co-opting (replacement histopathological growth patterns: RHGP) tumors. To investigate the role of the host Ang1 expression, Ang1 knockout (KO) mice were injected intra-splenically with metastatic MC-38 colon cancer cells that develop co-opting liver metastases. We observed a reduction in the number of liver metastases and interestingly, for the first time, the development of angiogenic driven desmoplastic (DHGP) liver metastases. In addition, in-vitro, knockout of Ang1 in primary hepatocytes inhibited viability, migration and invasion ability of MC-38 cells. We also demonstrate that Ang 1 alone promotes the migration and growth of both human and mouse colon cancer cell lines These results provide evidence that high expression of Ang1 in the host liver is important to support vessel co-option (RHGP lesions) and when inhibited, favours the formation of angiogenic driven liver metastases (DHGP lesions).

Single-cell transcriptomes of the regenerating intestine reveal a revival stem cell

The turnover of the intestinal epithelium is driven by multipotent LGR5⁺ crypt-base columnar cells (CBCs) located at the bottom of crypt zones¹. However, CBCs are lost following injury, such as irradiation², but the intestinal epithelium is nevertheless able to recover³. Thus, a second population of quiescent '+4' cells, or reserve stem cells (RSCs), has previously been proposed to regenerate the damaged intestine^4-7. Although CBCs and RSCs were thought to be mutually exclusive^4,8, subsequent studies have found that LGR5⁺ CBCs express RSC markers⁹ and that RSCs were dispensable-whereas LGR5⁺ cells were essential-for repair of the damaged intestine³. In addition, progenitors of absorptive enterocytes¹⁰, secretory cells^11-15 and slow cycling LGR5⁺ cells¹⁶ have been shown to contribute to regeneration whereas the transcriptional regulator YAP1, which is important for intestinal regeneration, was suggested to induce a pro-survival phenotype in LGR5⁺ cells¹⁷. Thus, whether cellular plasticity or distinct cell populations are critical for intestinal regeneration remains unknown. Here we applied single-cell RNA sequencing to profile the regenerating mouse intestine and identified a distinct, damage-induced quiescent cell type that we term the revival stem cell (revSC). revSCs are marked by high clusterin expression and are extremely rare under homoeostatic conditions, yet give rise-in a temporal hierarchy-to all the major cell types of the intestine, including LGR5⁺ CBCs. After intestinal damage by irradiation, targeted ablation of LGR5⁺ CBCs, or treatment with dextran sodium sulfate, revSCs undergo a YAP1-dependent transient expansion, reconstitute the LGR5⁺ CBC compartment and are required to regenerate a functional intestine. These studies thus define a unique stem cell that is mobilized by damage to revive the homoeostatic stem cell compartment and regenerate the intestinal epithelium.

Selenium supplementation and the incidence of preeclampsia in pregnant Iranian women: a randomized, double-blind, placebo-controlled pilot trial

OBJECTIVE

Recent studies have reported that antioxidant status, including serum selenium concentrations, is altered in women who develop preeclampsia. We wished to examine the effects of selenium supplementation in the prevention of preeclampsia in high-risk pregnant women.

DESIGN

We carried out a randomized, double-blind, placebo-controlled pilot trial. A total of 166 primigravid pregnant women, who were in the first trimester of pregnancy, were randomized to receive 100 microg of selenium (n = 83; dropouts, n = 22) or a placebo (n = 83; dropouts, n = 19) per day until delivery. The incidence of preeclampsia, serum selenium concentrations, lipid profile and high-sensitivity C-reactive protein status were evaluated at baseline and at the end of the study.

RESULTS

Supplementation with selenium was not associated with any reported major side effects and was associated with a significant increase in mean serum selenium concentrations at term (p < 0.001). In contrast, mean serum selenium concentrations remained unchanged in the control group (p = 0.63). The incidence of preeclampsia was lower in the selenium group (n = 0) than in the control group (n = 3), although this was not statistically significant (p > 0.05). After treatment, systolic and diastolic blood pressure, serum total cholesterol, triglycerides, low-density and high-density lipoprotein cholesterol, and high-sensitivity C-reactive protein were significantly increased in both groups compared with pretreatment levels (p < 0.05).

CONCLUSION

Our findings indicate that selenium supplementation in pregnant women may be associated with a lower frequency of preeclampsia.

Prooxidant-antioxidant balance in pregnancy: a randomized double-blind placebo-controlled trial of selenium supplementation

OBJECTIVE

We assessed the impact of selenium, a trace element with antioxidant properties on a simple measure of oxidative stress in pregnant women.

STUDY DESIGN

A novel assay of prooxidant-antioxidant balance (PAB) was applied in a double-blind, placebo-controlled study of selenium supplementation in pregnancy. We measured the prooxidant burden and the antioxidant capacity simultaneously in one assay, thereby calculating a redox index. A total of 166 primigravid pregnant women in the first trimester of pregnancy, were randomized to receive 100 microg of selenium (n=83) or placebo (n=83) per day until delivery. PAB values and serum selenium concentrations were measured at baseline and at the end of study.

RESULTS

Pretreatment demographic data and biochemical indices including serum selenium concentrations did not differ significantly between the groups. The drop-out rates for the groups were 22/83 and 19/83 for the selenium and placebo groups, respectively. Supplementation with selenium was associated with a significant increase in mean serum selenium concentration (P<0.001) but without significant change in mean PAB value. In contrast, mean serum selenium concentration remained unchanged and mean PAB values increased significantly (P<0.05 in the control group).

CONCLUSION

Our findings suggest that selenium supplementation may reduce oxidative stress associated with pregnancy.

Selenium supplementation and premature (pre-labour) rupture of membranes: a randomised double-blind placebo-controlled trial

The aim was to determine if selenium supplementation during pregnancy reduces the occurrence of premature (pre-labour) rupture of membranes (PROM). A total of 166 primigravid pregnant women in the first trimester of pregnancy, were randomised to receive 100 microg of selenium (n = 83, drop-outs = 22) or a placebo (n = 83, drop-outs = 19) per day until delivery. The incidence of PROM, as well as serum selenium concentrations were evaluated at baseline and at the end of the study. Supplementation with selenium was associated with a significant increase in mean serum selenium concentration at term (p < 0.001). In contrast, mean serum selenium concentration remained unchanged in the control group (p > 0.05). The incidence of PROM was significantly lower in the selenium group (n = 8, 13.1%) than in the control group (n = 22, 34.4%) (p < 0.01). Our findings indicate that selenium supplementation (100 microg/day) in pregnant women effectively reduces the incidence of PROM.