Hijacking the Host Defenses Gives Bacteria an Advantage

Amazing stuff! About some of the tricks bacteria use!

"... In the case of such invasion, large protective cells called macrophages try to stop the infection by swallowing the Salmonella whole. The bacteria, however, sometimes manage not only to survive but to thrive inside the macrophages, even converting them into incubators that facilitate their spread. ... The scientists checked all the metabolites that accumulate in macrophages when they fight Salmonella, and they zeroed in on a compound called succinate. This compound is known to act as a signaling molecule that the macrophages use to activate their defenses against invading bacteria: Succinate promotes the recruitment of the immune system and the generation of toxic inflammatory compounds that can kill the bacteria. ... bacteria –in the course of evolution – had learned to make use of this very molecule as a signal to become more virulent and to manipulate the contents of the macrophages to their own benefit. Succinate ... activates certain bacterial genes, causing the Salmonella to grow a needle that punctures vacuoles –closed compartments within the macrophage that keep bacteria wrapped in “hazmat” padding. The needle then secretes substances that neutralize the giant cell's killing mechanism. On top of this, succinate activates a mechanism that protects the Salmonella from antimicrobial peptides secreted within macrophages, so that the bacteria now feel free to treat the macrophage as a hotel, with all the amenities. ..."

"... Here, using metabolic profiling and dual RNA sequencing, we show that succinate accumulation in macrophages is sensed by intracellular Salmonella Typhimurium (S. Tm) to promote antimicrobial resistance and type III secretion. S. Tm lacking the succinate uptake transporter DcuB displays impaired survival in macrophages and in mice. Thus, S. Tm co-opts the metabolic reprogramming of infected macrophages as a signal that induces its own virulence and survival, providing an additional perspective on metabolic host–pathogen cross-talk. ..."

Hijacking the Host Defenses Gives Bacteria an Advantage A metabolic switch in microbe-fighting macrophages signals bacteria to convert them to hotels with amenities

Here is the link to the underlying research paper:

Host succinate is an activation signal for Salmonella virulence during intracellular infection (behind paywall)