Neuroimmunology

The immune system is a complicated network with the capacity to protect our body against infectious agents. Loss of self-tolerance can result in the immune response being directed against the very organism that generated it, giving rise to autoimmunity. Autoantibodies, i.e., molecules capable of recognizing specific molecular portions (antigens), are key players in these processes, as they can play a variety of roles, ranging from direct involvement in pathogenesis to roles as useful diagnostic biomarkers. Considering the particular functioning of the immune system within the central nervous system, and the presence of natural barriers (blood-brain and blood-CSF), the development and role of antibodies directed against neuronal targets is a complex and fascinating field of research.

Recent years have seen a huge increase in the identification of antibodies against neuronal proteins, thanks to the introduction of innovative immunoassays, such as cell-based assays and immunostaining of murine nerve tissue. These methods make it possible to identify conformational autoantibodies, i.e., antibodies able to recognize the target protein only when its three-dimensional structure is preserved.

Our unit is concerned mainly with the implementation and validation of new immunoassays, the standardization of existing ones, and investigation of the role of autoantibodies in various neurological diseases.

MAIN LINES OF RESEARCH

Autoimmune encephalitis, autoimmune psychosis and paraneoplastic syndromes

The term autoimmune encephalitis refers to a group of recently identified inflammatory brain diseases that enter into differential diagnosis with different forms of dementia, viral encephalitis and psychiatric syndromes. Autoantibodies can be directed against cell-surface neuronal proteins (like NMDAR, LGI1 and CASPR2) or against intracellular antigens (like Hu, Yo and Ma2).

Furthermore, only recently, forms of encephalitis have been identified that are likely of autoimmune etiology, but negative for autoantibodies.

Forms of autoimmune encephalitis can constitute a diagnostic challenge, especially when they present with predominantly psychiatric manifestations.

By means of cutting-edge testing methods, which combine fixed- and live-cell-based assays with immunohistochemistry of rat brain and neuronal cultures, our unit is concerned mainly with:

• clinical characterization of patients with autoimmune encephalitis, both forms with anti-neuronal antibodies and the seronegative forms
• identification of autoimmune encephalitis in the psychiatric setting, and investigation of the relevance of anti-neuronal antibodies found in psychiatric syndromes such as schizophrenia
• identification of rare antibodies in autoimmune encephalitis and of new antibody targets

Demyelinating diseases

The main demyelinating disease of the nervous system is multiple sclerosis (MS). It has a complex and multi-factorial pathogenesis that involves various components of the immune system. Recent discoveries have shown a crucial role of B lymphocytes, and evidence from several quarters suggests that autoantibodies directed against myelin proteins may also play a role, at least in a proportion of patients. Furthermore, in recent years, the identification of antibodies directed against glial proteins, such as AQP4 and MOG, has made it possible to define new pathological groups to be considered in differential diagnosis with MS.

In this area, our unit is involved in:

• analysis of diagnostic and prognostic biomarkers in MS, such as IgM oligoclonal bands
• characterization of autoantibody responses in patients with MS
• clinical characterization, identification of biomarkers and improvement of laboratory diagnostics in syndromes associated with antibodies directed against AQP4, MOG and GFAP
• investigation of the pathogenicity of antibodies directed against myelin proteins

Myasthenia gravis and myasthenia-like syndromes

Myasthenia is a disorder characterized by immune-mediated dysfunction of the neuromuscular junction, often caused by AchR and MuSK antibodies. A proportion of patients, however, are seronegative. In recent years, the use of cell-based assays has made it possible to identify new immune responses in patients with myasthenia, such as antibodies against “clustered” AchR and against LRP4.

In this area, our unit is involved in:

• standardization of diagnostic autoantibody detection methods in myasthenia
• identification and characterization of new antibody targets in myasthenia, such as the netrin-1 receptor

Inflammatory neuropathies

In this heterogeneous group of disorders, autoantibodies directed against a specific region of the nerve, namely the paranodal region (neurofascin 155, 186, contactin, CASPR1), have been identified in recent years. These antibodies probably have a pathogenetic role, and identify a group of conditions with a different prognosis from other inflammatory neuropathies. However, their clinical significance is still being defined.

Through the use of methods such as specific cell-based assays and staining of peripheral nerve “teased fibers”, our unit in involved in:

• clinical characterization of inflammatory neuropathies associated with antibodies against paranodal antigens
• identification of antibody targets in peripheral neuropathies

Specialized equipment:

• Complete isoelectric focusing system
• PCR instrumentation
• Instruments for vertical electrophoresis and Western blotting
• ELISA reader
• Cytocentrifuge for CSF cytology
• Laminar flow hood and CO₂incubator (for cell cultures)
• Chemical fume hood
• Cryostat and microtome
• Fluorescence microscope
• Housing and facilities for animal testing (in collaboration with the University of Pavia)
• Freezers with temperatures of -30°C and -80°C