Have you ever wondered why people get sick when they're stressed? Well, researchers at UT Southwestern Medical Center claim to have found the answer.
While studying the diarrhea-causing strain of E coli, they identified a receptor known as QseE, which resides in the bacterium.
The receptor senses stress cues from the bacterium's host and helps the pathogen make the host ill.
Dr. Vanessa Sperandio, associate professor of microbiology at UT Southwestern and the study's senior author, said QseE is an important player in disease development because the stress cues it senses from a host, chiefly epinephrine and phosphate are generally associated with blood poisoning, or sepsis.
"Patients with high levels of phosphate in the intestine have a much higher probability of developing sepsis due to systemic infection by intestinal bacteria," said Dr. Sperandio.
"If we can find out how bacteria sense these cues, then we can try to interfere in the process and prevent infection.
"There's obviously a lot of chemical signaling between host and bacteria going on, and we have very little information about which bacteria receptors recognize the host and vice versa.
"We're scratching at the tip of the iceberg on our knowledge of this," she added.
According to the researchers, once QseC recognizes the stress hormones, it initiates a cascade of genetic activations in which the bacteria colonizes the intestine and moves toxins into human cells, altering the makeup of the cells and robbing the body of nutrients.
"The bacteria get what they want, nourishment, and the person ends up getting diarrhea," Sperandio said.
"The problem may not only be that the stress signals are weakening your immune system, but that you're also priming some pathogens at the same time," she said.
"Then it's a double-edged sword. You have a weakened immune system and pathogens exploiting it," she added.