Neighborhood clustering analysis to define epithelial-stromal interface for tumor infiltrating lymphocyte evaluation

Area of Science:

• Oncology
• Immunology
• Computational Pathology

Background:

• Current tumor-infiltrating lymphocyte evaluation focuses on stromal regions, neglecting epithelial areas and the epithelial-stromal interface.
• Technical challenges in manual cell identification hinder assessment of immune cells within epithelial tumor cell mixtures.
• This limitation may impact patient response evaluation for immune checkpoint therapies.

Purpose of the Study:

• To apply supervised neighborhood clustering analysis (CytoMAP) for quantifying immune cell distribution in gynecological tumors.
• To assess the spatial distribution of CD8+ T cells, exhausted CD8+ TIM3+ T cells, and CD8- TIM3+ macrophages.
• To compare immune cell densities across epithelial, stromal, and epithelial-stromal interface compartments.

Main Methods:

• Utilized CytoMAP, an open-source application, for supervised neighborhood clustering analysis.
• Applied a three-compartment model (epithelial, stromal, interface) to partition tumors.
• Quantified spatial distribution of CD8+ T cells, CD8+ TIM3+ exhausted T cells, and CD8- TIM3+ macrophages on a gynecological tumor microarray.

Main Results:

• The epithelial-stromal interface compartment showed the highest density of CD8+ T cells when included in the three-compartment model.
• In contrast, the conventional two-compartment model primarily identified the stromal region as having the highest CD8+ T cell density.
• A higher proportion of CD8+ TIM3+ exhausted T cells were found in the interface and epithelial regions compared to CD8+ TIM3- T cells.

Conclusions:

• Quantitative spatial analysis and immune subset analysis are valuable for assessing tumor-infiltrating lymphocytes.
• The tumor epithelial-stromal interface is a significant, yet under-reported, compartment for immune cell infiltration.
• Incorporating the interface into analysis may improve understanding of patient response to immunotherapies.