(SACRAMENTO, Calif.) Nearly half of all HIV-positive African adults who become infected with Salmonella die from what otherwise would be a seven-day bout of diarrhea. Now, UC Davis School of Medicine scientists have discovered how salmonella becomes lethal for AIDS patients. Their findings also implicate a mechanism by which HIV evades the powerful drugs used to treat AIDS.
We have found the defect in the immune response that allows Salmonella to cross the mucosal barrier of the gut, enter the bloodstream and infect other organs, said Andreas Bumler, a UC Davis professor of medical microbiology and immunology and co-author of the study.
The results of the study, which will be published online by Nature Medicine March 23, revealed that viral infection of the intestine results in the depletion of a type of white blood cell, called Th-17, in the gut mucosa. This T helper lymphocyte produces IL-17, a cytokine or chemical messenger that plays a crucial role in the inflammatory response, recruiting other immune system cells to the site of infection.
This kind of interruption in the guts immune response could be allowing HIV to maintain reservoirs that evade drug treatments, said Satya Dandekar, professor and chair of the department of medical microbiology and immunology.
Its like putting out the fire, but leaving the embers smoldering, Dandekar said.
The rise in patients with acquired immune deficiency syndrome (AIDS) in sub-Saharan Africa has led to a dramatic increase in the frequency of non-typhoidal Salmonella serotypes (NTS), the strains of the bacteria that cause acute food-borne disease world wide. Normally, this infection is limited to the intestine, causing gastroenteritis. In AIDS patients, however, the infection spreads to the bloodstream and causes what is called NTS bacteremia.
While at a conference, Bumler was surprised to learn from epidemiologist and physician Melita Gordon of the University o
|Contact: David Ong|
University of California - Davis - Health System