Ozone Pollution Disrupts Genes Controlling Circadian Rhythms

Study finds air pollution, specifically ozone exposure, has a disruptive effect on the genes responsible for circadian rhythms in the lungs.
As the sun rises and sets, a symphony of biological processes unfolds within our bodies, choreographed by internal timekeepers called circadian clocks. These circadian rhythms are important for maintaining different internal biological cycles that regulate various physiological processes, such as metabolism, immunity and inflammation. When circadian rhythms are disrupted, it can lead to adverse health effects, including increased susceptibility to diseases.
In a recent scientific study published in Advanced Biology, scientists have gained new insights into the impact that air pollution has on the genes that control circadian rhythms, commonly called “clock genes”, and the downstream physiological effects, suggesting a relationship with inflammation that occurs in the lungs after exposure, Advanced Science News reported.
The study looked at ozone, a common environmental pollutant primarily produced by vehicle emissions and industrial activities, and known for its harmful effects on respiratory health, particularly in individuals with asthma.
“Understanding how the genes and proteins that regulate the circadian clock in the lungs behave might shed light on the unknown mechanism that can control environmental exposure-induced lung injury,” said Isaac Sundar, associate professor in the Department of Internal Medicine at the University of Kansas Medical Center and first author of the study.
The findings are particularly intriguing because the study found a different level of susceptibility between genders. 
“Our study shows for the first time that when exposed to air pollutants, such as ozone, there are changes that occur in the lungs that are quite different in female and male mice,” said Sundar. 
“Specifically, the changes we observed are related to circadian clock genes [suggesting] that the lung may show differential responses to environmental insults depending on the time of the day.”
Many previous studies have shown that ozone exposure triggers inflammation in the lungs, but these recent findings have provided a crucial link that infers circadian rhythm may be involved in this mechanism. 
The researchers monitored the effect of ozone exposure on the clock genes activated or inhibited in lung cells in mice.
After both long- and short-term exposure, they observed changes associated with dysregulation in clock gene expression by monitoring mRNA levels in cells, which are linked to protein production and cell function. In almost every part of the lungs, ranging from structural tissues to immune cells, they observed these changes, which were surprisingly, starker in the female mice.
“Work from experimental models [rodents] has shown that female hormones make the lungs generate more inflammatory mediators in response to ozone exposure, an evolutionary adaptation to protect females from infection,” said Patricia Silveyra, a faculty member of the flagship campus of Indiana University-Bloomington at the School of Public Health, and lead author of the study. 
“However, pollution tends to elucidate responses that mimic what happens during infection, so it ends up damaging the lungs instead of protecting them.”