MU researcher helps night-shift workers by studying how exosomes affecttheir internal clocks

MU researcher David Gozal said night-shift workers are more likely to suffer from insomnia, diabetes, obesity and a slew of other health problems. Night shifts and other nontraditional work hours also put them at risk for developing additional physical and mental disorders.

“To be a shift worker is not a good thing [for the body to undergo regularly], yet our modern society is increasingly dependent on shift workers,” Gozal said. “If you look how things were two centuries ago, shift work was virtually non-existent,” he added.

Gozal’s research on exosomes is a crucial step toward making sense of the misalignment process. He has identified tiny messengers that travel among our cells and hopes to use that knowledge to readjust and balance circadian rhythms.

According to a study by the Population Reference Bureau, 75 percent of employees begin their work shifts at traditional times between 6 and 10 a.m. The rest work during nontraditional times, with these jobs projecting the largest occupational growth in the next decade.

Although we continue to make shift work more commonplace, Gozal said, we do not understand how the message between the central clock in the brain and the peripheral clocks in all our organs gets misaligned.

“There are clocks in every cell,” Gozal said. We have the central “master clock” in the brain and peripheral clocks in the various organs, tissues and cells throughout the body.

These clocks can be misaligned when someone travels through multiple time zones or when they miss regularly scheduled sleep times. Thus, pilots and members of the armed forces typically struggle with internal clock issues in addition to night-shift workers. In September, Gozal published research identifying exosomes as the messengers that deliver misaligned biological times to various parts of the body. These times differ from that of the central clock in the brain, creating the misalignment that night-shift workers experience.

“Exosomes are tiny, tiny vesicles — envelopes if you wish,” Gozal said.

At about 30 to 100 nanometers, these microscopic, sphere-like packages tell you which cell they came from and, with the right work, can also tell you which cells they are heading to next. Exosomes can carry various content such as fats, sugars, proteins and DNA. These materials can relay messages, deliver materials or cause physical changes depending on the content.

Gozal tested whether exosomes could change the peripheral clocks in fat cells by simulating night-shift work in a group of people. He had their blood drawn and extracted the exosomes from those samples. Then he injected the exosomes into naïve fat cells in the incubator to observe the peripheral clock times and metabolic rate. His research showed that exosomes are responsible for changing biological clock times and causing insulin resistance in fat tissue. Research shows that night-shift workers eat more, and their insulin sensitivity is affected, Gozal said. Over time, some night-shift workers become insulin resistant — craving more sugar and fat because they don’t process energy appropriately in their fat cells. Night-shift work, however, affects each person differently. Some are more susceptible to problems associated with biological clock changes, Gozal said, whereas others have little to no issues from working nontraditional work hours.

Kitten Riney, an auditor for the Hampton Inn in Columbia, has worked nights at the hotel for more than 20 years. She does the work of seven employees during her shift because she is the only employee on the clock for her three-night work week. She and another coworker cover the nights shifts throughout the week. Riney remembers when she applied for the job years ago. She specifically chose the late shift because she’s always been a bit of a night owl.

“As a kid, I was a night person,” said Riney. She would go to bed at a normal bedtime and still be wide awake at midnight. “It’s like my clock is 12 hours different,” she said.

Riney said she doesn’t typically have a problem sleeping when she’s off work. She tries to keep her sleep schedule consistent — resting from noon to 7 p.m. and using the weekend to catch up on any extra sleep she needs.

Although Gozal notes the many problems stemming from night-shift work and other work that alters the body’s internal clock, he understands that the work these people do is vital to keeping the world turning. He hopes to use this research eventually to help treat those who are struggling. He said he wants to use his knowledge of exosomes to not only identify which people will be likely to experience circadian misalignment from working at nontraditional times but also treat patients by changing the content of their exosomes.

That will help workers in critical roles continue to perform their jobs at a high level, he said.

Source – University of Missouri Extension

Khalyfa A, Gaddameedhi S, Crooks E, Zhang C, Li Y, Qiao Z, Trzepizur W, Kay SA, Andrade J, Satterfield BC, Hansen DA, Kheirandish-Gozal L, Van Dongen HPA, Gozal D. (2020) Circulating Exosomal miRNAs Signal Circadian Misalignment to Peripheral Metabolic Tissues. Int J Mol Sci 21(17):6396. [article]

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