Scientists identify new features of lymphangioleiomyomatosis (LAM) a rare lung disease

By National Heart, Lung, and Blood Institute


Also known as Lymphangioleiomyomatosis LAM, or lymphangioleiomyomatosis, is a rare lung disease that affects mostly women of childbearing age. In people who have LAM, abnormal muscle-like cells begin to grow out of control in certain organs or tissues, especially the lungs, lymph nodes, and kidneys. Over time, these LAM cells can destroy the healthy lung tissue. As a result, cysts may develop in the lungs, preventing air from moving freely in and out of the lungs. This may prevent the delivery of oxygen to the rest of the body.

There are two types of LAM, and your signs and symptoms may depend on which type you have. Symptoms of LAM may include shortness of breath, fatigue, cough, and bleeding into the kidneys. Doctors may diagnose LAM with pulmonary function tests, imaging tests, and blood tests.

A lung transplant is the only cure for LAM disease. Your doctor may prescribe medicine to help prevent further damage to your lungs and to treat other symptoms or complications. It is important to get routine follow-up care, because the disease often worsens over time. How quickly the disease worsens varies. Many women who have LAM will develop a serious condition called pneumothorax, or collapsed lung, that requires immediate treatment. Over time, LAM may cause permanent damage to the lungs or respiratory failure.

WHAT: Researchers have discovered new insights about lymphangioleiomyomatosis (LAM), a rare lung disease, which affects about 1 in 200,000 Americans and commonly features the growth of abnormal cells in different tissues and organs, including the lungs.  

As researchers studied LAM cells in the lab, they discovered a “mixed phenotype,” or differences in physical expression in the lymphatic endothelial cells. These cells appeared to resemble cells in lymphatics as well as blood endothelial cells. The characteristics were also noted in a small percentage of lung cells provided by people living with idiopathic pulmonary fibrosis (IPF), another rare lung disease. However, the researchers didn’t observe this phenotypical crossover when studying cells from healthy volunteers or from people living with Kaposi’s sarcoma, a blood-related cancer.  

When LAM cells accumulate in the lungs, cysts can form and impede airflow, making it hard to breathe. To help people living with LAM and other rare lung conditions, researchers have been studying physical characteristics of LAM. LAM cells in the lung reside in nodules, which are small clusters of LAM and other cells that line the cysts and may be disseminated. These lung nodules also contain lymphatics, part of the lymphatic system, which supports circulation and immune function. Lymphatic endothelial cells line the nodules and provided new insight about LAM.  

Researchers are hopeful that ongoing research and future studies will lead to personalized therapies for people living with LAM and other rare lung conditions. They also recommend studying and will continue to follow the role lymphatics may have in disease progression, which could support the development of new and improved therapies.  

THE STUDY: The paper, “A mixed blood-lymphatic endothelial cell phenotype in LAM and IPF but not in Kaposi’s sarcoma or TSC,” published Feb. 1 in the American Journal of Respiratory Cell and Molecular Biology

WHO: Joel Moss, M.D., Ph.D., a senior investigator in the Laboratory of Translational Research, this study is ongoing LAM research
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