By Sarah Carnvek

Israeli researchers are often cited for their studies into the medicinal properties of cannabis. Now, a Tel Aviv University team of scientists has shown that some chemical compounds found in marijuana can help treat multiple sclerosis-like diseases by preventing inflammation in the brain and spinal cord.

Multiple sclerosis is an inflammatory disease in which the immune system attacks the nervous system. The result can be a wide range of debilitating motor, physical and mental problems.

"Inflammation is part of the body's natural immune response, but in cases like MS, it gets out of hand," says co-author Dr. Ewa Kozela, who previously studied opiates like morphine, derived from the poppy plant. "Our study looks at how compounds isolated from marijuana can be used to regulate inflammation to protect the nervous system and its functions."

Kozela, Ana Juknat, Neta Rimmerman and Zvi Vogel of Tel Aviv University's Dr. Miriam and Sheldon G. Adelson Center for the Biology of Addictive Diseases and Sackler Faculty of Medicine, together with researchers from the Weizmann Institute of Science, published their findings in the Journal of Neuroimmune Pharmacology.

Since 1964, when Israeli scientists Raphael Mechoulam and Yechiel Gaoni discovered the main psychoactive ingredient in the cannabis plant, tetrahydrocannabinol, or THC, Israelis have been leading the way in research into the medicinal properties of cannabis.

Since then, scientists have identified some 85 compounds — called cannabinoids — that are unique to cannabis and have remarkable biological effects.

Mechoulam later deciphered the cannabinoids native to the brain. And Ruth Gallily, a professor emerita of immunology at the Hebrew University of Jerusalem, studied cannabidiol, or CBD — considered to have a wider scope of medical applications than THC.

CBD is less psychoactive than THC and is hailed as a powerful anti-inflammatory and anti-anxiety agent. The TAU researchers focused on CBD because it offers medicinal benefits without the controversial mind-altering effects of THC.

In a 2011 study, they showed that CBD helps treat MS-like symptoms in mice by preventing immune cells in their bodies from transforming and attacking the insulating covers of nerve cells in the spinal cord. After inducing an MS-like condition in mice — partially paralyzing their limbs — the researchers injected them with CBD. The mice responded by regaining movement, first twitching their tails and then beginning to walk without a limp. The researchers noted that the mice treated with CBD had much less inflammation in the spinal cord than did their untreated counterparts.

In the latest study, the researchers set out to see if the known anti-inflammatory properties of CBD and THC could also be applied to the treatment of inflammation associated with MS — and if so, how.

The university researchers took isolated immune cells -- which target and harm the brain and spinal cord -- from paralyzed mice, and treated them with either CBD or THC.

In both cases, the immune cells produced fewer inflammatory molecules, particularly one called interleukin 17, or IL-17, which is strongly associated with MS and very harmful to nerve cells and their insulating covers. The researchers concluded that the presence of CBD or THC restrains the immune cells from triggering the production of inflammatory molecules and limits the molecules' ability to reach and damage the brain and spinal cord.

While the results look good and there are reasons for hope, the researchers say further studies are needed to prove the effectiveness of cannabinoids in treating MS in humans.

In many countries, CBD and THC are already prescribed for the treatment of MS symptoms, including pain and muscle stiffness.

And a previous Israeli study at the University of Haifa showed that if the substance is given during a certain window of time after a traumatic event, it blocks the development of post-traumatic stress disorder (PTSD) symptoms.

"When used wisely, cannabis has huge potential," says Kozela. "We're just beginning to understand how it works."