When Matthew Chapman was studying the bacteria that cause urinary tract infections five years ago as part of his post-doctoral research at Washington University, he never expected that it would lead him to study the bacteria’s connection to Alzheimer’s disease at the University of Michigan.
“The UTI thing was sort of an inroad, a first glimpse and the reason why we’re studying these proteins,” said Chapman, who is now an assistant professor in Molecular Cell and Developmental Biology.
While Chapman explored how the bacteria commonly known as E. coli colonize the bladder, he observed that the bacteria were producing a certain type of misfolded fiber that is associated with incurable diseases like Alzheimer’s, Huntington’s and Creutzfeld-Jacob, the human version of Mad Cow disease.
“It was one of those completely sort of ‘Eureka’ surprising moments,” Chapman said.
Amyloid fibers present in the neurological systems of patients afflicted with such diseases are formed when proteins are converted into a misfolded shape, and continue converting other proteins, creating a chain in a process that damages surrounding brain cells.
Chapman said the “self-perpetuating reaction” that these fibers engage in explains the rapid onset of dementia and loss of cognitive abilities from the time symptoms of Alzheimer’s are first seen.
“Once you get it started, you’re sort of up the creek,” he said.
Now that Chapman has discovered fiber production in bacteria, researchers can begin to investigate what sets off the condition.
Chapman said that while the fiber formation process is more complicated in humans, researchers will be able to understand it better by observing the process in bacteria.
Chapman said that while it is advantageous to bacteria to produce amyloid fibers, it is unclear what prompts the production of the fibers in humans and why it is harmful.
Answering those questions could revolutionize the way Alzheimer’s is treated, Chapman said.
While amyloid fiber formation has been considered a toxic process associated with disease for decades, Chapman has hypothesized that forming amyloids is not always bad.
Chapman’s bacteria have shown him that the fibers produced as the end result of the process are not harmful to the cell, but rather the process itself.
Many treatments being researched for Alzheimer’s disease attempt to slow down the process of fiber formation, but Chapman said doing so might lengthen the time that cells are at risk of being damaged.
“Instead, look for things that facilitate that process, that would lessen the toxicity,” he said. “In bacteria, we can show that we can skip over the toxic steps by providing facilitator proteins.”
A paper detailing the research findings was published online last week in the Proceedings of the National Academy of Sciences. It was authored by Chapman, Rackham graduate student Neal Hammer and Jens Schmidt, a visiting student from Germany were published online last week in the Proceedings of the National Academy of Sciences.
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