Tsolis and her collaborators were the first to discover PPARγ's role in brucellosis and to determine that AAMs harbor the bacteria during the chronic stage of the disease. The identification of the bacteria's niche is another important clue for the development of a more effective treatment, she said.
In a series of experiments, Tsolis and collaborators found that the gene encoding PPARγ is very active during chronic Brucellosis infection, but not during acute infection, and that the B. abortus bacteria did not survive in AAMs when deprived of glucose.
When the researchers inactivated the protein that normally transports glucose, the bacteria stopped reproducing, and the infection no longer was chronic, she said.
In mice infected with B. abortus, Tsolis and collaborators treated the animals with GW9662, a PPAR inhibitor. The researchers administered the inhibitor before the infection became chronic, or long lasting. The inhibitor significantly reduced the amount of AAMs and B. abortus bacteria in the mice.
"These results suggested that inhibition of PPARreduced the bacteria's survival by reducing the abundance of AAMs during chronic infection," said Tsolis.
Conversely, when the researchers treated the B. abortus-infected mice with Rosiglitazone, a drug that boosts PPAR activity, the bacteria increased by two-fold during the acute phase and four-fold during the chronic phase of infection. Rosiglitazone and other drugs that boost PPARare used to treat type 2 diabetes because they lower blood glucose by increasing cellular glucose uptake.
In other experiments, the researchers showed that AAMs, one of two categories of macrophages, are abundant in the spleen during chronic brucellosis but not during the acute, or initial, phase of the infection, which is dominated by
|Contact: Carole Gan|
University of California - Davis Health System