Analyzing a protein from the cerebrospinal fluid will help diagnose patients with prion diseases

• A team of scientists demonstrates for the first time that neurogranin is a very reliable biomarker for prion diseases in humans
• This protein is found in neurons, and can be easily detected at the cerebrospinal fluid of alive patients

Every year in Catalonia 15 new cases of Creutzfeldt Jakob Disease are diagnosed. It is a mortal prion disease whose cause is unknown and has no treatment. It is very similar to the mad cow disease provoked by prions, also known as CJD variant. The challenge has always been to diagnose prion diseases when a person or an animal is suffering from them, since the current the diagnose is done once the patient is dead.

Recently, a study published in the Journal of Neurology, Neurosurgery & Psychiatry demonstrates that very high levels of neurogranin in the cerebrospinal fluid can be detected in human patients that suffer from prion diseases. The work has been led by researchers from The Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED)) of the Institute of Health Carlos III (ISCIII), the Bellvitge Biomedical Research Institute (IDIBELL) and the UMG-Göttingen in Germany, with the participation of the PRIOCAT laboratory of the Animal Health Research Center (IRTA-CReSA). So far, some studies have already shown that patients with neurodegenerative diseases such as Alzheimer’s have higher levels of this protein in the cerebrospinal fluid. “We have now verified that the same but magnified happens in people who suffer from the sporadic Creutzfeldt Jakob”, says Franc Llorens, researcher at CIBERNED and IDIBELL.

Neurogranin is a protein found naturally in neurons. His role is to participate in the process of the synapse and can be detected by analyzing the cerebrospinal fluid, “a fluid that surrounds and protects our central nervous system and fills up its cavities or ventricles, therefore it can give us much information about what is happening to the brain”, explains Enric Vidal, researcher at IRTA-CReSA. There are currently several methods to help diagnose prion diseases, but they are not completely reliable. In fact, these diseases can only be diagnosed with absolute certainty by analyzing the brain of the dead patient. “This finding will help us make more accurate diagnoses, since it is a biological sample that can be obtained when the patient is alive and is relatively easy to collect with a lumbar puncture”, the authors of the study confirm.

More information on the prognosis of the disease

According to experts, today it is impossible to predict the duration of prion diseases, since they depend on many factors and some of them are still unknown. In this study, however, it has been detected that the levels of neurogranin are associated with the duration of the disease. “Neurogranin is a marker of neuronal damage. When we find it in high quantities, it is indicating that neurons are harmed, therefore the disease will move faster, it will have a short duration”, explains Franc Llorens. This information will help the experts to predict the clinical evolution of the Creutzfeldt Jakob cases and to better select patients according to their condition, as well as to better interpret clinical trials to find anti-prion therapies.

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Some phases of this study have been carried out in the biosafety level prion laboratory 3, located in the facilities of the Center for Research in Animal Health (IRTA-CReSA). PRIOCAT is the only laboratory in Catalonia that works with animal prions and maintains an agreement with CIBERNED to carry out experiments with these highly pathogenic agents also in samples obtained from human patients.