A new report from Japanese doctors shows that asbestos affects immunity. It may help explain why exposure to asbestos can trigger mesothelioma.
Asbestos is the primary cause of malignant mesothelioma worldwide. But doctors still do not know for sure how this fibrous mineral causes cancer.
Scientists know that inflammation and irritation have something to do with mesothelioma development. But they still do not know much about how asbestos affects immunity.
Asbestos and Mesothelioma Development
Asbestos is a silicate mineral that lies deep in the ground. For decades, people mined asbestos for use in various industries. Nearly every building in the US built before the mid-1980s contains some asbestos.
Mesothelioma researchers have not spent much time on how asbestos affects immunity. Most studies focus on the physical impact of the fibers and their components.
Microscopic asbestos fibers are thin and sharp. Once inhaled or swallowed, they can stay in the body forever. They become a chronic irritant. This causes changes in the cells that make up the mesothelial membranes. The result can be mesothelioma many years later.
The iron in asbestos fibers is also toxic. Some think this may contribute to the development of malignant mesothelioma.
Exploring How Asbestos Affects Immunity
Silica is a mineral that is chemically similar to asbestos. People exposed to silica often develop lung and autoimmune diseases. “It is clear that silica exposure impairs immune tolerance,” write the researchers from Okayama University and Kawasaki Medical School.
They reasoned that it is possible asbestos affects immunity, too. Certain immune system cells help keep cancer at bay. If asbestos compromises these cells, mesothelioma may gain a foothold.
“Given that malignant tumors can result following exposure to asbestos, the attenuation [reduction] of anti-tumor immunity in cases of asbestos exposure is an important area of investigation,” the authors write.
To see how asbestos affects immunity, they created a series of experiments with asbestos fibers and immune system cells.
“We observed the effect of asbestos fibers on T lymphocytes, such as CD8+ cytotoxic T lymphocytes (CTLs), CD4+ helper T (Th), and regulatory T (Treg) cells, and showed that anti-tumor immunity was attenuated [reduced],” writes investigator Naoko Kumagai-Takei.
The report appears in the International Journal of Molecular Sciences. It suggests that the development of pleural mesothelioma may be even more complicated that scientists realize. Understanding the process may bring them closed to a cure.
About 2,500 people in the US face a mesothelioma diagnosis each year.
Naoko Kumagai-Takei, et al, “The Effects of Asbestos Fibers on Human T Cells”, September 23, 2020, International Journal of Molecular Sciences, https://www.mdpi.com/1422-0067/21/19/6987