If you have an overactive bladder or incontinence, help
could be on the way. A new research report published online in the FASEB Journal, shows that the
epithelium, a thin layer of cells which line the surface of the bladder, is
able to sense how full the bladder is through the action of a family of
proteins called integrins.
As the bladder becomes full, the cells in the epithelium stretch and become
thinner, which activates the integrins to send that information to nerves and
other cells in the bladder. As a result of this new knowledge, researchers may
one day be able to design drugs that target this mechanism to treat conditions
like incontinence and overactive bladder, both of which are common, serious,
problems affecting millions of people.
"I am very hopeful that as we learn more about how the
bladder senses fullness and conveys that information to the nerves and the
muscles which control our ability to urinate, that this greater understanding
and knowledge will lead to new treatments," said Warren G. Hill, Ph.D., a
researcher involved in the work from the Department of Medicine at Beth Israel
Deaconess Medical Center and Harvard Medical School in Boston, MA.
"It is extremely important that we do this as quickly as possible, since
there are millions of people who suffer enormously from the anguish of bladder
pain, incontinence and constant feelings of needing to go. I am optimistic
these new insights into the role of integrins will begin the process of
discovering important new drug targets which will dramatically improve the
quality of life for many of these people."
To make this discovery, Hill and colleagues tested two
groups of mice. The first were genetically modified to not have an important
member of the integrin family present in the epithelium. The second group of
mice was normal. The mice lacking the integrin protein had normal looking
bladders but very little urinary control.
The normal mice also had normal looking bladders, but as
expected, had bladder control. Researchers then tested the bladders from the
integrin knockout mice and found that their bladders were constantly squeezing
and very overactive. In addition, they overfilled their bladders and took much
longer to urinate than the normal mice.
Since most drug treatments for overactive bladder target
proteins in the muscle surrounding the bladder, this study shows that it may be
possible to design drugs that target sensory proteins in the epithelium.
"No one wants to pee in his or her pants," said
Gerald Weissmann, M.D., Editor-in-Chief of the FASEB Journal, "but the reality is that bladder problems –
incontinence, frequency and pain - affect more people than we realize. This
report offers hope that new drugs targeting the bladder's epithelium will
succeed when current drugs fail."