Richard M. Ransohoff, MD, when starting up his lab at Cleveland Clinic, decided to investigate whether two unknown genes were expressed or regulated in the CNS of mice with experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS).
A colleague there had just isolated the transcripts for the genes and showed they were strongly responsive to the inflammatory cytokine interferon-gamma.
It was 1992. The process was slow the in situ hybridization probes being used were very reliable but took a month for every experiment, recalled Dr. Ransohoff, director of the Neuroinflammation Research Center at the Cleveland Clinic Lerner Research Institute and professor of medicine at Case Western Reserve University.
But finally, the first full experiment, with controls, was done it was time for him and his gifted post-doc Mari Tani, MD, now a practicing neurologist — to see the results. The mice were “really sick” with EAE, and Dr. Ransohoff knew that if the genes in question had prompted any activity, they would see it.
They searched other departments until they found a microscope that had dark-field imaging capability but had to wait until after 5 PM to use it.
When they finally did, they were disappointed at first: the control slide showed lots of background, and the experimental slides showed no signal at all.
Then they double-checked a notebook they had gotten their probes reversed. The sense probe, or negative probe, was mislabeled and was actually the antisense, positive probe. So, as it turned out, the background was very low and the signal very strong, Dr. Ransohoff recalled, the memory still ablaze.
“We realized that all the signal was in the brain cells it was an incredibly specific and discrete and powerful, well-localized signal,” he said. “I mean, it was just thrilling. You could literally see the brain cells standing up and signaling to the leukocytes and saying, ‘Hey, we're here.’”
That dark-field imaging microscope wasn't even necessary — the signal was easily visible without it and the bright-field images showed that every hybridization grain was found within astrocytes.
The unknown genes, it was later found, were chemokines now known to be important in recruiting immune-system cells to sites of inflammation. Dr. Ransohoff has spent his research career finding out about them.
“The minute I saw that experiment — the data, looked at the slides with my post-doc — I was completely hooked,” he said. “Because it really was one of the very first demonstrations that inflammation in the brain wouldn't be just about a bunch of white cells entering the brain then using cytokines to talk to each other, [but] that the immune system really did talk to the brain and the brain talked back.”
His work with chemokines, all stemming from that discovery 20 years ago, earned him the John Dystel Prize for MS Research, a $15,000 award given by the National Multiple Sclerosis Society and the AAN.
CHEMOKINES, REGENERATING MYELIN
Dr. Ransohoff's work now involves two projects that explore the role of chemokines in the regeneration of myelin. One takes a look at CXCR2, a chemokine receptor present on neutrophils, the cells associated with acute inflammation. Dr. Ransohoff's lab is examining the role of this receptor in a variety of models of demyelination.
So far, they've found that when the receptor is blocked or deleted, the kind of inflammation involved in myelin injury is reduced and remyelination is accelerated.
That's interesting from the standpoint of drug-targeting because you can imagine you sort of get two for the price of one you get reduced demyelination and enhanced remyelination,s Dr. Ransohoff said.
But Dr. Ransohoff is known as a disciplined researcher who doesn't mind a plodding pace if the work is important. And he is being patient with this line of inquiry.
“We need to understand the receptor somewhat better before we start targeting it in humans because it is an important mediator of immunity,” he said.
In the other project, he is looking at the role that chemokines and their receptors might play in neural stem cells' ability to repair myelin. The work, which is still in the pre-funding stage, involves manipulating the chemokine environment in the stem cell region, or “niche,” to see whether myelin repair is enhanced.
‘SERENDIPITY’ AND GOOD FORTUNE
“I couldn't possibly dream of a better set of projects to work on or better people to work with, or a better career,” Dr. Ransohoff said.
He describes his success as the product of Hguided serendipityg sure, hard work and intellect is involved, but so is good fortune.
In the discovery of the role of chemokines in the animal MS models, he said he was lucky to have the assistance of Dr. Tani, the post-doc. She was interested in MS research, and his was the only MS lab in town. And she happened to be well-versed in molecular techniques for analyzing the expression of and finding the cellular source of the transcripts they were studying.
In another stroke of luck, Barrett Rollins, MD, PhD, a friend from medical school, had run into dead-ends trying to find a link between cancer and a certain gene — until he discovered that it was a chemo-attractant protein, which became one of the founding elements of the chemokine field.
Dr. Rollins, now at Harvard's Dana-Farber Cancer Institute, connected Dr. Ransohoff to his colleagues in the burgeoning chemokine field, resulting in an invitation for Dr. Ransohoff to present his data at a major meeting. Dr. Ransohoff said he was “kind of adopted as the neuro guy in the chemokine field,” and they supplied him with great reagents, such as the newest antibodies, and generously-proffered technical advice.
Dr. Ransohoff credits much of his discipline and determination to a mentor at Cleveland Clinic, George Stark, PhD, who frequently encouraged younger colleagues to pursue worthy goals.
Dr. Ransohoff also said his late start doing serious research he didn't do any major bench work until he was 38 might have something to do with his patience. “I've realized that you can take the long road and things will come out okay,” he said.
He has also remained at Cleveland Clinic throughout his career — which allowed him to stay on a research path without getting swept up by other endeavors, he said.
“It isn't Boston, San Francisco, New York or San Diego,” he said. “Cleveland is a place where you're a little bit out of the raging storm and you have time to develop your own projects and really mature the work in your own garden.”