How ultrafine particles in airborne smoke alter the host's defense against lung cancer

While it may seem common sense that smoking is harmful to the lungs, whether and how ultrafine particles in cigarette smoke affect the development and progression of lung cancer is unclear
.
Researchers at Baylor College of Medicine used animal models to try to find out how ultrafine particles in airborne smoke alter the host's defense against lung cancer
.

In a study published in the latest issue of the journal Science Advances, Dr.
Zheng-yen Chang, a postdoctoral fellow in Dr.
Farah Heramand's lab in the Department of Pulmonology at Baylor College of Medicine, and their team found that exposure to ultrafine particles alters the function of immune cells in the lungs, rendering their natural defense mechanisms against tumors ineffective
.
They found that ultrafine particles change the cell's main source of energy, creating new byproducts
in the lungs.
The accumulation of new byproducts reduces the host's immune defenses, allowing tumors to escape detection
.

These particles are not only found in cigarette smoke; Environmental and other natural fires also incompletely burn organic matter
that produces ultrafine particles.
Kheradmand and colleagues at Rice University previously found that the immune cells in the lungs of heavy smokers contained nanoscale elemental carbon black particles
.

"When we breathe, we inhale many particles
of different sizes.
They can stay somewhere in the respiratory tract, such as the nose or trachea, depending on their size
.
”

"Ultrafine particles are so small that they can travel through the respiratory system and be deposited at the distal end of the lungs for gas exchange – the process of
breathing," Heramand said.
"It is at this time that these particles gather and begin to change the function of
lung immune cells.
"

This study sheds light on how ultrafine particles contribute to cancer progression

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

Both mouse models showed accelerated lung cancer progression when mice were exposed to nanocarbon black
.

"What we're seeing is that immune cells change what
they use to get energy.
They changed from using fat, which is fat in cells in general, to using sugar
.
The new byproduct alters immune cells, making the tumor unrecognizable
.
"This exposure makes the tumor more aggressive and more likely to metastasize or spread throughout the body
.
"

Another surprise was that it didn't matter whether the mice were prone to cancer or not; Even without any tumors, exposure to ultrafine particles still causes changes
in the energy use of immune cells from fat to sugar.

"These particles change the dynamics of cells and change their internal mechanisms," Kheradmand said
.

The study only looked at how ultrafine particles affect immune cells and the development of cancer; Further research is needed to look at other factors such as particle concentration, length of exposure, and type
.

"We're just studying the significance of having these particles in the respiratory tract — whether they cause and worsen disease
.
" We knew they were found in smokers' lungs, so our study simulated exposure similar to that of heavy smokers
.
”

Chang and Kheradmand showed in a past study that there is a way to make these particles more soluble so they can be cleared
from the lungs.
However, this is only a laboratory model, just the first step in potential future treatments, not a way
to make smoking safe.
"In general, as far as smoking is concerned, there is no way to guarantee that any level of exposure is safe
," Kheradmand said.
"It's best to avoid contact
from the start.
"