Abstract B001: Macrophage adipocyte crosstalk as a node of intervention for pancreatic cancer-associated weight loss
Authors: Hambitzer Felix P. , Faghihi Farhad , Parent Brendan D. , Walsh Michael , Roth Susanne , Aguirre Andrew , Michalski Christoph W. , Loos Martin , Dougan Stephanie K. , Mills Evanna , Heckler Max 
Published: September 2024

Abstract
Introduction: Up to 85% of patients with pancreatic ductal adenocarcinoma (PDAC) are afflicted with cachexia - a metabolic syndrome characterized by loss of skeletal muscle mass and adipose tissue wasting. Cachexia worsens patients’ quality of life, their ability to tolerate chemotherapy or surgical procedures, and, ultimately, their survival. Existing therapies often fail as the disease remains insufficiently understood. Drawing insights from obesity research, where changes in the local adipose immune environment play a crucial role in the pathophysiology, we explore the adipose tissue in the context of PDAC cachexia at single-cell resolution to uncover novel therapeutic avenues. Methods: We developed an ex vivo co-culture system to examine the effect of macrophages on adipocyte lipolysis by measuring the amount of released glycerol from adipocytes following incubation with macrophage supernatant. This robust platform can be used to interrogate factors directly affecting glycerol release from adipocytes. To identify candidate mediators of macrophage-adipocyte crosstalk, we profiled murine and human adipose tissue by flow cytometry and single-cell/nucleus RNA sequencing. The tissue samples were obtained from a cohort of genetically engineered KPC mice and a representative group of surgical patients. Patient adipose samples were collected intraoperatively without warm ischemic time at Heidelberg University Hospital. The cohort includes over 60 patients, divided into three groups: (1) PDAC with weight loss, (2) PDAC without weight loss, and (3) control patients without a history of malignancy. Of these, 25 samples are being used for single-nucleus RNA sequencing. The groups are balanced by sex and can be stratified into equally sized subgroups based on whether they had received neoadjuvant treatment. Results: Macrophage- conditioned media significantly elevated lipid release from murine adipocytes, demonstrating that macrophages may play a role in cancer-associated adipose wasting. Single-nucleus RNA sequencing data from our mice and from our human clinical cohort reveals distinct cell clusters with condition-specific subpopulations and differences unique to cancer-associated weight loss. The biggest phenotypic shifts were observed in macrophages and in adipocytes which showed signs of oxidative stress and altered metabolism associated with cachexia. Conclusion: We successfully established reliable workflows for processing and investigating murine and human AT in the context of PDAC cachexia. Our in vitro model highlights a distinct phenotype of murine macrophage supernatant inducing increased glycerol release from adipocytes. The in-depth analysis of our single-nucleus RNA sequencing data from our clinical cohort promises an unprecedentedly detailed and robust understanding of the human adipose immune environment, thereby enhancing our insights into PDAC cachexia.
Citation Format:Felix P. Hambitzer, Farhad Faghihi, Brendan D. Parent, Michael Walsh, Susanne Roth, Andrew Aguirre, Christoph W. Michalski, Martin Loos, Stephanie K. Dougan, Evanna Mills, Max Heckler. Macrophage adipocyte crosstalk as a node of intervention for pancreatic cancer-associated weight loss [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr B001.