Carbon Ultrafine Particles Accelerate Lung Cancer Progression

In a new study Dr. Farrah Kheradmand and their team discovered that exposure to ultrafine particles alters the function of immune cells in the lungs, disabling their natural defense mechanism against tumors. They found that ultrafine particles change the cell’s primary energy source, creating new byproducts in the lungs. Accumulation of the new byproducts can decrease the host’s immune defense, allowing tumors to escape detection.

These particles are not just found in cigarette smoke; environmental and other natural fires also incompletely combust organic matter that generates ultrafine particles. Kheradmand and colleagues at Rice University had previously found that immune cells in the lungs of heavy smokers contain particles that they identified as nano-sized elemental carbon black.

“Ultrafine particles are so small they can navigate the respiratory system and deposit in the far distal part of the lung that is used for gas exchange — the process of breathing,” Kheradmand said. “It is at that point where these particles can collect and begin to alter the way lung immune cells function.”

Using two different mouse models of lung cancer, Chang was able to replicate the same type of exposure to ultrafine particles typically seen in a heavy smoker.

Both mouse models showed accelerated lung cancer progression when mice were exposed to nano-sized carbon black.

“What we saw was that the immune cells changed what they used for energy. They went from using fat, which is what is seen in the average cell, to using sugar. The new byproducts alter immune cells allowing for tumors to escape recognition,” Chang said. “This exposure made tumors more aggressive and more likely to metastasize or spread throughout the body.”

Another surprise was that whether mice were predisposed to develop cancer didn’t matter; exposure to ultrafine particles still led to changes in energy usage from fat to sugar in immune cells even in the absence of any tumor.

“The particles change the powerhouse of the cells, altering their internal machinery,” Kheradmand said.

The study only looked at how the ultrafine particles affected immune cells and cancer development; further studies are still needed to look at other factors such as the concentration of particles and length and type of exposure.


Cheng-Yen Chang, Ran You, Dominique Armstrong, Ashwini Bandi, Yi-Ting Cheng, Philip M. Burkhardt, Luis Becerra-Dominguez, Matthew C. Madison, Hui-Ying Tung, Zhimin Zeng, Yifan Wu, Lizhen Song, Patricia E. Phillips, Paul Porter, John M. Knight, Nagireddy Putluri, Xiaoyi Yuan, Daniela C. Marcano, Emily A. McHugh, James M. Tour, Andre Catic, Laure Maneix, Bryan M. Burt, Hyun-Sung Lee, David B. Corry, Farrah Kheradmand. Chronic exposure to carbon black ultrafine particles reprograms macrophage metabolism and accelerates lung cancer. Science Advances, 2022; 8 (46) DOI: 10.1126/sciadv.abq0615

Materials provided by Baylor College of Medicine. Original written by Graciela Gutierrez. Note: Content may be edited for style and length.

Baylor College of Medicine. “Carbon ultrafine particles accelerate lung cancer progression.” ScienceDaily. ScienceDaily, 29 November 2022. <>.

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