Daylight Primes the Body’s First Line of Defense: New Research

If immune system cells appreciated music, they’d probably love “Here Comes the Sun” as much as the rest of us do. A new study suggests daylight boosts the infection-fighting power of neutrophils, the body’s most common white blood cells. Neutrophils have internal clocks that respond to light. When the sun is up, these clocks activate and help neutrophils kill bacteria more effectively.

Researchers at Waipapa Taumata Rau, University of Auckland, conducted the study. They used transparent zebrafish, which have immune systems similar to humans. Zebrafish are ideal for studying how cells behave in real time.

The study’s findings could lead to new treatments that target neutrophil clocks to improve immunity. Neutrophils are key players in defending the body against bacterial infections. By understanding how light affects their activity, scientists may unlock new ways to boost the immune system.

How Did Researchers Link Daylight and Neutrophil Activity?

The study’s researchers genetically edited neutrophils to remove parts of their circadian clock. They compared this to removing cogs from an analog clock so it stops ticking. Without their clock parts, neutrophils lose the ability to boost bacterial defense during the day.

The circadian clock is thought to be 2.5 billion years old. Its core components are transcription factors called CLOCK and BMAL1. These proteins control the timed expression of clock-controlled genes, or CCGs.

Key CCGs include PER2 and CRY1. In mice, removing CLOCK components reduces the immune system’s improved daytime defense against Salmonella. CLOCK genes also regulate immune functions in cells like lymphocytes, dendritic cells, and monocytes.

During the day, neutrophils patrol tissues to look for bacteria. After spotting an infection, the gene PER2 helps neutrophils make reactive oxygen species, or ROS. Neutrophils release ROS after engulfing bacteria, helping kill them.

When neutrophils lack PER2, they make less ROS. This makes it easier for bacteria to survive and grow.

What Other Neutrophil Factors Do Researchers Want to Explore?

Researchers infected zebrafish larvae and exposed them to light. The larvae showed boosted expression of immune system clock genes. This suggests light directly drives neutrophil activity, not just an internal clock.

Neutrophils have a light-sensitive clock that works like an alarm. When it goes off, it boosts their ability to fight bacteria during the day. The body’s clock helps match immune strength to infection risk.

The researchers want to explore how light signals are detected by neutrophils. They also want to know if this timing mechanism applies to other infections.

These findings could lead to new drugs that target neutrophil clocks. This may improve treatments for infections and inflammation. Neutrophils are the first immune cells to respond to infection. They are also the most abundant immune cells at inflamed sites. This discovery has broad implications for treating inflammatory diseases.

Conclusion

A new study reveals how daylight primes the body’s first line of defense. Understanding neutrophil clocks may lead to better treatments for infection and inflammation. With further research, scientists hope to unlock new ways to strengthen immunity.

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Logan Hamilton is a health and wellness freelance writer for hire. He’s passionate about crafting crystal-clear, captivating, and credible content that elevates brands and establishes trust. When not writing, Logan can be found hiking, sticking his nose in bizarre books, or playing drums in a local rock band. Find him at loganjameshamilton.com.