Neuroscientists have found that patients born without the CCR5 gene recover better from mild stroke than patients with it.

US university UCLA teamed up with Israeli researchers to study the missing gene’s effect on brain function.

CCR5 plays multiple roles in the body and is known as the gene which unlocks the cellular doorway that the HIV virus enters to infect the immune system.

It is the same gene that Chinese scientists reportedly altered with a genetic engineering technique known as CRISPR to genetically modify human embryos.

The current study builds upon earlier UCLA research in mice showing that suppressing CCR5 enhances neurons’ ability to form new connections and rewire the brain after injury.

The 2016 study also demonstrated that the FDA-approved HIV drug maraviroc, which targets CCR5 to slow HIV progression in patients, improved learning and memory in mice.

Maraviroc blocks CCR5 and, therefore, this latest study hypothesises whether the drug may also accelerate recovery from stroke. Researchers tested the drug’s effectiveness in suppressing CCR5 in a mouse model.

“This is the first time that a human gene has been linked to a better recovery from stroke,” said senior author Dr Thomas Carmichael, chair of the neurology department at the David Geffen School of Medicine at UCLA. “Our discovery offers exciting potential for improving patients’ health and enhancing their quality of life.”

“We found that maraviroc blocked CCR5 in mice and boosted the animals’ recovery from traumatic brain injury and stroke. The big question left to answer was whether eliminating CCR5 would produce the same results in people.”

Knowing that the absence of the CCR5 gene is common in Ashkenazi Jews, Carmichael and his team contacted researchers at Tel Aviv University. Here, scientists were already following 446 stroke patients in an observational study.

Led by neuroscientist Einor Ben Assayag, the study focused on patients who had suffered mild or moderate strokes,  documenting improvements in walking, arm and leg control, and other types of movement.

“Einor’s lab had the patients’ blood samples and was evaluating their recovery from stroke after intervals of six months, one year and two years,” said Carmichael. “People missing the CCR5 gene showed significantly greater recovery in motor skills, language and sensory function.”

One year after stroke, patients missing CCR5 also scored higher in tests assessing memory, verbal function and attention.

Neurons produce CCR5 only during or after stroke. Deletion of CCR5 appears to promote recovery by enhancing plasticity — the ability of the brain to rewire itself after injury.

The scientists’ next step will be to launch a clinical trial testing the effectiveness of the drug maraviroc on stroke patients with the CCR5 gene.