Persistent Bacterial Infection Exploits Killing Machinery Of Immune Cells
A new study reveals an important and newly discovered pathway used by disease-causing bacteria to evade the host immune system and survive and grow within the very cells meant to destroy them.
Clearing the body of disease-causing bacteria is the job of specialized white blood cells called macrophages. The word "macrophage" means "big eater" in Latin and that is just what these cells are--they gobble up cell debris, infected cells and disease-causing bacteria found in the body. To help them digest and destroy what they eat, macrophages make compounds that in most cases kill pathogens. One of these chemicals is the free radical nitric oxide (NO).
However, some harmful bacteria, known as intracellular pathogens, live inside cells and can even survive and replicate within macrophages, somehow inhibiting or escaping killing by NO. One natural NO inhibitor made by macrophages is the enzyme arginase. Arginase steals and degrades the material required to make NO, therefore limiting how much NO is made
The research team discovered that intracellular pathogens increase levels of arginase, thereby reducing the amount of NO the macrophages produce, enabling intracellular pathogens to survive. The presence of persistent intracellular bacteria is particularly harmful to people with compromised immune systems, such as people with HIV or cancer, who often contract chronic bacterial and parasitic infections.
Full article: http://www.sciencedaily.com/releases/2008/11/081102134630.htm
A new study reveals an important and newly discovered pathway used by disease-causing bacteria to evade the host immune system and survive and grow within the very cells meant to destroy them.
Clearing the body of disease-causing bacteria is the job of specialized white blood cells called macrophages. The word "macrophage" means "big eater" in Latin and that is just what these cells are--they gobble up cell debris, infected cells and disease-causing bacteria found in the body. To help them digest and destroy what they eat, macrophages make compounds that in most cases kill pathogens. One of these chemicals is the free radical nitric oxide (NO).
However, some harmful bacteria, known as intracellular pathogens, live inside cells and can even survive and replicate within macrophages, somehow inhibiting or escaping killing by NO. One natural NO inhibitor made by macrophages is the enzyme arginase. Arginase steals and degrades the material required to make NO, therefore limiting how much NO is made
The research team discovered that intracellular pathogens increase levels of arginase, thereby reducing the amount of NO the macrophages produce, enabling intracellular pathogens to survive. The presence of persistent intracellular bacteria is particularly harmful to people with compromised immune systems, such as people with HIV or cancer, who often contract chronic bacterial and parasitic infections.
Full article: http://www.sciencedaily.com/releases/2008/11/081102134630.htm