Estrogen therapy may reduce susceptibility and inflammatory responses to urinary tract infections in postmenopausal women, mouse study suggests.(2013)
From the article:
To simulate menopause in mice, scientists surgically remove their ovaries. Like menopausal women, the mice no longer make estrogen.
To rule out the possibility that the stress of surgery affects the risk of urinary tract infections, the researchers conducted the same surgery in other mice but put the ovaries back in, maintaining their ability to make estrogen.
When researchers gave both groups of mice urinary tract infections, the menopausal mice had higher levels of infectious bacteria in their urine. Most of the bacteria came from barrier cells, which line the interior of the bladder. These cells are the first to be infected by the bacteria.
“When the barrier cells are lost, they need to be replaced immediately,” Mysorekar says. “In the menopausal mice, we found that this replacement process was stopping short of completion. That left cells under barrier cells exposed, and they are much more vulnerable to infection.”
Enjoying this research? Get deeper insights like this delivered every other week.
Every other week our Premium Members receive deep dives like this alongside Rhonda's commentary and 8+ other hand-picked papers.
The menopausal mice had more bacterial reservoirs, which are pockets of infection that may provide a place for the bacteria to hide during antibiotic treatment. After treatment stops, the reservoirs can reseed the infection.
In earlier research, Mysorekar had identified an important regulator of the barrier cell repair process. In the new study, she showed that low estrogen levels disable this regulator.
The bladders of the menopausal mice also had higher levels of immune inflammatory compounds known as cytokines.
“The cytokines caused inflammation that left the bladder in bad shape,” Mysorekar says. “It’s possible that damage caused by inflammation increases the bacteria’s ability to break into bladder tissue and create reservoirs of infection.”
In the control mice, which had normal estrogen levels, cytokine levels and inflammatory damage were both significantly lower. When researchers gave the menopausal mice estrogen, their cytokine levels and inflammatory damage also decreased significantly, as did reservoirs of infectious bacteria.