Tumor microenvironment highlighting tumor-associated macrophages and immune cells

Abstract

Cholangiocarcinoma (CCA) grows within a highly desmoplastic microenvironment, exhibiting a continuous interconnection with the immune infiltrate, which is characterized by an abundance of immune cells, including natural killer cells, T lymphocytes, and macrophages. The presence of inflammatory cells within the tumor microenvironment plays a crucial role in determining the aggressiveness and growth of CCA. The immune cell population engages in diverse and dynamic interactions with cancer cells. The balance of different subpopulations within CCA can generate varying responses, either inhibiting or promoting tumoral progression. The purpose of this review is to offer a comprehensive overview of the role of various immune infiltrate subpopulations within the tumor microenvironment, with a particular focus on the actions of tumor-associated macrophages (TAMs) and their critical regulation in the development and progression of CCA. TAMs play vital roles in maintaining homeostasis, facilitating tissue repair, and contributing to immune responses due to their significant functional diversity. Macrophages are present in numerous types of cancer, and their emerging role has also been observed in CCA. Recognizing and attaining a deeper comprehension of the intricate interplay between infiltrating immune cells and CCA cells is essential to identify new opportunities to advance treatment strategies.