A new biomarker for brain and spinal cord inflammation has been identified by researchers at Mayo Clinic. This discovery could lead to faster diagnosis and treatment of patients.The findings have been published in the JAMA Neurology.Vanda Lennon and colleagues identified the new biomarker in spinal fluid and blood serum of patients with a neurological disorder called autoimmune meningoencephalomyelitis. The biomarker is an antibody.
‘A newly identified biomarker in spinal fluid and blood serum of patients may lead to faster diagnosis of brain and spinal cord inflammation.’
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Antibodies are molecules used by the immune
system to fight infections or cancer. When an antibody is directed
against healthy tissue by a misguided immune system, as it is in this
disorder, it is called an autoantibody. In autoimmune meningoencephalomyelitis, the autoantibody targets a protein called glial fibrillary acidic protein within cells called astrocytes that are found in the brain and spinal cord.
"Headache is a prominent symptom reported by the patients," says Dr. Lennon, who is senior author on the study. "It is accompanied by neurological findings of varying severity. Inflammatory cells in the spinal fluid and MRI images raise suspicion for brain infection, other inflammatory brain disease or a cancer spreading to the lining of the brain."
Dr. Lennon notes that this disease rapidly reverses with therapy directed at the immune system, such as prednisone, in contrast to infections that need antibiotics and cancer that requires aggressive treatment. A positive test for glial fibrillary acidic protein autoantibody should bring the correct diagnosis earlier and hasten the most appropriate treatment.
The glial fibrillary acidic protein antibody biomarker initially was identified in Mayo Clinic's Neuroimmunology Laboratory, which is within the Department of Laboratory Medicine and Pathology. The biomarker was identified using a test developed in the 1960s.
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The probe antibody is tagged with a fluorescent dye. When viewed under a fluorescence microscope, the tagged antibody shows the location of the bound human autoantibody, revealing the cells targeted by the immune system. In this case, the pattern of binding to mouse brain tissue resembles the pattern of abnormalities seen in MRI images of the patients' brain and spinal cord.
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With the discovery of this biomarker, Dr. Lennon and the team expect that diagnosis and treatment for patients will improve in another important way. "At this stage, we've identified about 103 patients," says Dr. Lennon. "And about a third of them are turning out to have an unsuspected cancer in a remote part of the body."
The research team suspects that, because cancer cells and the nervous system use some of the same mechanisms for communication, the immune response that is attacking a cancer is causing collateral damage to the nervous system in the process.
"It appears from evidence to date that the antibody does not itself cause the brain inflammation," says Dr. Lennon. "It is a proxy marker of a more aggressive component of the immune system called killer T cells, which target the same brain protein."
The next steps are to verify the glial fibrillary acidic protein autoantibody's diagnostic performance. At that point, Mayo Clinic's Neuroimmunology Laboratory anticipates offering this test for diagnostic purposes.
Source-Eurekalert