Why getting healthy is worse than getting sick

Washington, Mar 21 (ANI): Researchers have explained why our immune system usually makes us worse while trying to make us hale and hearty.

The research offers a new perspective on a component of the immune system known as the acute-phase response, a series of systemic changes in blood protein levels, metabolic function, and physiology that sometimes occurs when bacteria, viruses, or other pathogens invade the body.

This response puts healthy cells and tissue under serious stress, and is actually the cause of many of the symptoms we associate with being sick.

"The question is why would these harmful components evolve," asked Edmund LeGrand (University of Tennessee, Knoxville), who wrote the paper titled with Joe Alcock (University of New Mexico).

The researchers contend that answer becomes clear when we view the acute-phase response in terms of what they call "immune brinksmanship."

The immune brinksmanship model "is the gamble that systemic stressors will harm the pathogens relatively more than the host," LeGrand said. The concept, he explained, is akin to what happens in international trade disputes.

When one country places trade sanctions on another, both countries' economies take a hit, but the sanctioning country is betting that its opponent will be hurt more.

The acute-phase response creates stress in several ways. It raises body temperature and causes loss of appetite and mild anemia.

At the same time, certain vital nutrients like iron, zinc, and manganese are partially sequestered away from the bloodstream.

LeGrand and Alcock said that for an infection to spread, pathogens need to multiply, whereas host cells can defer replication.

Replication makes DNA and newly forming proteins much more susceptible to damage. It also requires energy and nutrients-which helps explain the benefits of restricting food and sequestering nutrients.

The act of invading a body also requires bacteria to alter their metabolism, which can make them more vulnerable to all kinds of stress, including heat.

Another reason pathogens are more vulnerable to stress is that the immune system is already pummelling them with white blood cells and related stressors at the site of the infection.

That means that pathogens are already under local stress when systemic stressors are piled on.

As the term "brinksmanship" implies, there's an inherent risk in a strategy that involves harming oneself to hurt the enemy within. This self-harm leaves the body more vulnerable to other dangers, including other infections. Additionally, it is possible for the immune stressors to do more damage than required to control the pathogens.

"But in general, systemic stressors when properly regulated do preferential harm to invaders," LeGrand added.

The study has been published in The Quarterly Review of Biology. (ANI)