As per a new study published in the journal of News Medical Life sciences, a researcher by the Columbia University have discovered a previously unknown cell type that acts as a bodyguard for lung tumors, shielding them from immune system attacks.
While scientists have known for years that these surrounding cells often aid cancer progression and signal poorer patient outcomes, the exact mechanics remained elusive.
Within the context of a lung tumor, however, the cancer hijacks this protective mechanism.
The influx of regulatory T cells creates a localized shield of immunosuppression, preventing the rest of the immune system from identifying and destroying the malignant cells.
When examining human tumor specimens and patient records from the extensive tissue bank at Columbia, the team confirmed that the same CHL1 fibroblasts exist in human lung cancers.
As per a new study published in the journal of News Medical Life sciences, a researcher by the Columbia University have discovered a previously unknown cell type that acts as a bodyguard for lung tumors, shielding them from immune system attacks. The study, published in Nature Immunology, reveals a hidden defense mechanism used by lung cancers and opens up potential new avenues for treatment against the leading cause of cancer related deaths in the United States.The studyThe discovery grew out of a broader effort to understand the role of fibroblasts, which are seemingly ordinary structural cells frequently found surrounding solid tumors. While scientists have known for years that these surrounding cells often aid cancer progression and signal poorer patient outcomes, the exact mechanics remained elusive. To unpack this, lead investigator and Columbia graduate student Olivia Ringham utilized single cell transcriptomic profiling on mouse models. This high resolution technique allowed her to analyze individual fibroblasts one by one, ultimately revealing a distinct, hidden subpopulation that expressed a gene named CHL1. Crucially, this gene is completely absent in the fibroblasts of healthy lung tissue.Working alongside co researcher Alexander Arpaia and colleagues from Columbia and the University of Toronto, Ringham unraveled how these newly identified CHL1 fibroblasts protect the disease.The cells release a specific signaling protein called CXCL9, which acts as a molecular beacon. This beacon draws a heavy concentration of regulatory T cells directly to the border of the tumor.The findingsIn a healthy body, regulatory T cells perform a vital peacekeeping role in the lungs, keeping the immune system balanced so that every inhaled environmental antigen does not trigger a massive inflammatory response. Within the context of a lung tumor, however, the cancer hijacks this protective mechanism. The influx of regulatory T cells creates a localized shield of immunosuppression, preventing the rest of the immune system from identifying and destroying the malignant cells. When the researchers experimentally blocked this CXCL9 signaling network in mice by knocking out the relevant genes, the regulatory T cells could no longer accumulate, effectively disarming the shield and enabling immune cells to attack the tumor.ObservationsThese laboratory findings hold direct relevance for human medicine. When examining human tumor specimens and patient records from the extensive tissue bank at Columbia, the team confirmed that the same CHL1 fibroblasts exist in human lung cancers. Patients whose tumors harbored higher levels of these specialized cells exhibited diminished immune responses against their disease and suffered significantly lower progression free survival rates.Because CHL1 fibroblasts are entirely unique to cancerous environments and absent in healthy lungs, they offer a promising double target for future therapies. Scientists could potentially neutralize the regulatory T cells attracted by these fibroblasts to unleash the natural defenses of the body, or intervene earlier to prevent healthy fibroblasts from transforming into CHL1 cells in the first place, stopping the protective shield of the tumor before it ever forms.
