Science Sub-Journal: Immune system neutrophils and macrophages cooperate to trap and kill bacteria

Studies have found that just like spiders catch prey, neutrophils and macrophages of the immune system can cooperate to capture and "eat" bacteria

It is well known that neutrophils-the first responding immune cells that migrate to the site of infection-can self-destruct and release their protein and DNA content, creating neutrophil extracellular traps (NETs)

Staphylococcus aureus ("Staphylococcus") bacteria—especially antibiotic-resistant bacteria—is a major cause of hospital-acquired infections, infectious heart disease, and pus-forming skin and soft tissue infections

Both neutrophils and macrophages are phagocytes, known for absorbing bacteria and producing antimicrobial peptides (AMPs), reactive oxygen species and other enzymes to fight infection

"Professional phagocytes, such as neutrophils and macrophages (Mφs), have an armory of antibacterial processes that are essential to combat bacterial pathogens," the team wrote

The research team added that macrophages are also critical to the innate immune response of Staphylococcus aureus and stimulate most of its antibacterial activity after internalizing the pathogen

In their latest report, Monteith and colleagues used neutrophils increased in NETosis in animals and in vitro model systems to study the biological functions of NETs

The increase in NETosis also promotes the killing of other bacterial pathogens by macrophages, indicating that neutrophil/net-macrophage cooperation may be a widely used immune defense mechanism

The researchers also showed that eliminating a staphylococcal nuclease that can cut DNA makes the bacteria more susceptible to the killing of net macrophages

Blocking nucleases can make pathogens more sensitive to net-mediated killing, and may be a good antibacterial treatment strategy

The author concluded: "Our results show that in the presence of Mφs, the formation of NET acts as a conduit, broadly enhancing the antibacterial activity against bacterial pathogens

"Scientists are excited about the idea of ​​anti-virus strategies, because we know a lot about the virulence mechanisms of bacteria and can come up with creative ways to inhibit them," Skaar commented

Monteith, Skaar and colleagues are continuing to explore the problems of NETosis, including how and when neutrophils choose this form of cell death