41: Defining the immune microenvironment surrounding pancreatic cancer using single cell RNA sequencing

Thursday, March 23, 2023

10:56 AM – 11:06 AM

Location: Ballroom B

Abstract Presenter(s)

Timothy L. Frankel, MD

Maude T. Lane Professor of Surgical Oncology
University of Michigan, United States

Disclosure(s): Applied Spectral Imaging: Research Grant (Ongoing)

First Author(s)

Timothy L. Frankel, MD

Maude T. Lane Professor of Surgical Oncology
University of Michigan, United States

Disclosure(s): Applied Spectral Imaging: Research Grant (Ongoing)

Author(s)

EC

Eileen Carpenter, MD, PhD

Assistant Professor
University of Michigan, United States

Disclosure information not submitted.
PK

Padma Kadiyala, BS

Graduate Student
University of Michigan, United States

Disclosure information not submitted.
AE

Ahmed Elhossiny, BPharm, MS

Graduate Student
University of Michigan, United States

Disclosure information not submitted.
JM

Jake McGue, BS

Research Technician
University of Michigan, United States

Disclosure information not submitted.
YZ

Yaqing Zhang, PhD

Research Assistant Professor
University of Michigan, United States

Disclosure information not submitted.
Brian D. Griffith, MD

General Surgery Resident
University of Michigan
Ann Arbor, Michigan, United States

Disclosure information not submitted.
JE

Jacob Edwards, BS

Research Technician
University of Michigan, United States

Disclosure information not submitted.
MP

Marina Pasca Di Magliano, PhD

Professor of Surgery
University of MIchigan, United States

Disclosure information not submitted.

Disclosure(s):

Timothy L. Frankel, MD: Applied Spectral Imaging: Research Grant (Ongoing)

Introduction: Uninvolved pancreatic tissue surrounding cancers is often used as a comparator to the tumor immune microenvironment. We sought to better define the peritumoral immune microenvironment utilizing true pathologically normal tissue from donated pancreases.

Methods: Through a partnership with Gift of Life Michigan, pancreases from brain dead deceased donors (n=30) were rapidly collected and subjected to standard immunohistochemistry (n=30), multiplex immunohistochemistry (n=15) and single cell RNA sequencing (n=6). These data were compared to tissue collected from pancreatic tumors (n=15) and adjacent uninvolved pancreas (n=3) which were subjected to similar analysis.

Results: Single cell RNA sequencing was performed on 44,668 cells from donor pancreatic tissue and revealed a broad array of infiltrating immune cells including lymphocytes, natural killer cells and myeloid cells. When compared to donor pancreases, adjacent uninvolved tissue had far greater infiltration of alternatively activated macrophages and granulocytes while the former was dominated by tissue resident macrophages. Principle component analysis revealed that the transcriptomic signature of myeloid cell subsets (classical, alternatively activated and resident macrophages) surrounding pancreatic tumors matched far more closely with intratumoral immune cells than with normal donor pancreatic tissue (Figure). Pathway analysis revealed that peri-tumoral myeloid cells expressed transcripts associated with vascular endothelial growth factor as well as recruitment of immune cells suggesting a potential role in shaping the tumor immune microenvironment. Specifically, among the top differentially expressed genes was interleukin 8, which is associated with both granulocyte recruitment and angiogenesis. Multiplex immunohistochemistry using markers for classical (CD163) and alternatively activated macrophages (Arginase) confirmed the transcriptomic findings.

Conclusions:

Previous attempts to describe the peritumoral immune infiltrate in pancreatic cancer have been limited as tumors and chronic inflammation exert strong regional effects. This is the first report detailing the transcriptomic signatures of immune cells in pathologically normal pancreas tissue revealing that immune cells surrounding tumors are almost indistinguishable from those within cancers.

Learning Objectives:

Understand differences in the immune microenvironment surrounding pancreatic tumors
Describe the transcriptional signature of immune cells in pathologically normal pancreases
Understand key differences between adjacent normal and true pathologically normal tissues