Immune cells that normally repair tissues in the body can be fooled by tumors when cancer starts forming in the lungs and instead help the tumor become invasive, according to a surprising discovery reported by Mount Sinai scientists in Nature.
The researchers found that early-stage lung cancer tumors co-opt the immune cells, known as tissue-resident macrophages, to help invade lung tissue. They also mapped out the process, or program, of how the macrophages allow a tumor to hurt the tissues the macrophage normally repairs. This process allows the tumor to hide from the immune system and proliferate into later, deadly stages of cancer.
Macrophages play a key role in shaping the tumor microenvironment, the ecosystem that surrounds tumors in the body. By investigating this microenvironment, researchers can find key players that drive tumor growth that can be tested as targets for immunotherapy. But modifying macrophages therapeutically has proven difficult.
In this study, scientists studied tissue samples from lung cancer tumors and surrounding lung tissue in 35 patients to see the role of macrophages in the development of the tumors.
The study’s lead author, Miriam Merad, MD, PhD, Director of the Precision Immunology Institute at the Icahn School of Medicine at Mount Sinai, and a multidisciplinary team of thoracic surgeons, pathologists, and medical oncologists within the Institute of Thoracic Oncology devised a comprehensive study that began when patients went into surgery to have cancerous lesions removed. The patients’ lung tumor samples, samples of surrounding healthy lung tissue, and blood samples were immediately analyzed on a cellular level at Mount Sinai’s Human Immune Monitoring Center to map out the immune system components they contained.