Study Shows ALS May Be an Autoimmune Disorder

Researchers at La Jolla Institute for Immunology (LJI) and Columbia University Irving Medical Center have discovered that amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease, may be an autoimmune disorder. The researchers found that inflammatory immune cells, called CD4+ T cells, mistakenly target certain proteins that are part of the nervous system in people with ALS.

“This is the first study to clearly demonstrate that in people with ALS, there is an autoimmune reaction that targets specific proteins associated with the disease,” says LJI Professor Alessandro Sette, PhD, who co-led the study with Professor David Sulzer, PhD, of the Columbia University Irving Medical Center.

In the study, the researchers examined T cell responses in ALS patients and found two distinct patient groups: one that had shorter predicted survival times with inflammatory CD4+ T cells quick to release inflammatory mediators when they recognized C9orf72 proteins, and a second group that also had harmful inflammatory CD4+ T cells, but also had higher numbers of anti-inflammatory CD4+ T cells. This second group also had significantly longer projected survival times.

Anti-inflammatory CD4+ T cells are important because they can regulate disease. For example, when the immune system fights a viral infection, it produces inflammatory T cells to eliminate the infected cells. Once the immune system clears the virus, anti-inflammatory CD4+ T cells prevent overzealous T cells from damaging healthy tissues. The researchers weren’t expecting to observe this same process in ALS patients, which suggests CD4+ T cells may reduce harmful autoimmune responses and slow the progression of ALS. “This protective T-cell response is strongest in people with a longer predicted survival time,” says Emil Johansson, PhD, a visiting scientist in the Sette Lab.

According to LJI Research Technician Tanner Michaelis, who served as the study’s first author, future ALS therapies might boost protective CD4+ T cell responses and dial back harmful inflammation. “Hopefully, now that we know the specific target for these immune cells, we can make more effective therapies for ALS,” says Michaelis. “This approach may be applicable for additional disorders such as Parkinson’s, Huntington’s and Alzheimer’s,” adds Dr. Sette.