A new study suggests that people lacking a certain gene can better recover from traumatic brain strokes and trauma than people with the gene.
The gene – called CCR5 – is the same gene at the center of the recent CRISPR controversy on babies, in which a Chinese scientist extracted the gene from two embryos to create HIV-resistant babies.
People who do not have the CCR5 gene show resistance to HIV – and indeed, an HIV drug called Maraviroc works by blocking the CCR5 receptor. (The CCR5 gene tells the cells to create the CCR5 protein, which binds to the CCR5 receptor.) [7 Things That May Raise Your Risk of Stroke]
In the new study, published Feb. 21 in the journal Cell, researchers found that when they administered Maraviroc to mice to block their CCR5 receptors, they had greater control over their gait and limbs. . Even if the mice have not suffered a stroke, the findings could shed light on the disease, as people with stroke may have difficulty moving and controlling parts of their body.
But the fact that something has an effect in animals does not mean that it will have exactly the same effect in humans. The researchers collaborated with Israeli scientists at Tel Aviv University, who were already following the recovery of nearly 450 patients with mild to moderate stroke.
Many of these patients did not have the CCR5 gene, said Dr. Thomas Carmichael, lead author, professor, and chair of neurology at the University of California at Los Angeles. (The gene is often absent among Ashkenazi Jews, and many of the patients in the study were Ashkenazim, Carmichael added.)
As might be suspected, the researchers found that gene-free patients seemed better able to recover from a stroke, both physically – in terms of controlling their movements – and mentally, with improvements in memory, verbal function and attention to patients with the gene.
Carmichael said that one of the possible explanations for the results is that a lack of the CCR5 gene prevents the loss of brain connections located near the stroke site and also stimulates new connections in more remote areas of the brain. Conversely, the brains of patients carrying the gene may have a reduced capacity for change and reorganization.
Dr. Heidi Schambra, director of neuroepidemiology at NYU Langone Health, who was not part of the study, said, "the findings suggest a new approach to promote stroke recovery and [traumatic brain injury]"But for Maraviroc to be used as a treatment for convalescent patients with stroke, it must first go through a clinical trial that directly tests the effectiveness of this treatment for that particular purpose." she told Live Science.
Indeed, the researchers are starting a phase 2 clinical trial to answer this question.
And while the absence of CCR5 may seem like a good thing, the gene could confer benefits, Carmichael said. Previous research, for example, suggests that this plays an important role in stopping the formation of memories.
Memories are formed when groups of brain cells bind after a stimulus. To stop memory formation, CCR5 tells this group of cells not to bind to a certain stimulus. If you enter your kitchen and you break an egg in a frying pan, "you want to remember that you did it," Carmichael said. But you do not want this memory to be also related to the loud noise that comes from the backyard. This is where we think that the CCR5 comes into play.
However, Carmichael noted that if the reports on gene-modified babies were true and the scientist had suppressed the CCR5 gene, the effects – beneficial or not – could affect much more than the immune system. "The brain and the immune systems are so complex, [so] it's hard to know, "he said.
Originally published on Science live.