Inflammatory responses to sepsis

In an earlier post (TLR4) I discussed the TLR4 receptor. This receptor detects microbes and starts an inflammatory response. TLR4 is not the only receptor that detects microbes. There are many receptors the immune system uses. This redundancy prevents microbes going undetected and matches the response to the microbe. At least, when everything works. An excessive response can cause sepsis. In sepsis the response is so strong that it damages tissues and can even cause organ failure.

I have recently collaborated with Oliver Voss and John Coligan from the National Institute of Allergy and Infectious Diseases. They were studying CD300b. This is another receptor that binds lipopolysaccharides (LPS) like TLR4. CD300b then binds to TLR4 and enhances its signaling. This enhanced signaling can then cause more tissue damage, leading to sepsis.

Inhibiting TLR4 does not work well for treating sepsis in humans. This might be because some TLR4 signaling helps combat infecting microbes. Inhibiting CD300b might strike a healthy balance between continuing to fight the infection and the excessive signaling causing tissue injury.