The study of neural antibodies in neurology: A practical summary

Autoimmune Encephalitis and Paraneoplastic Neurological Syndromes with Progressive Supranuclear Palsy-like Manifestations

BACKGROUND

Advances in diagnostic procedures have led to an increasing rate of diagnosis of autoimmune encephalitis or paraneoplastic neurological syndrome (AE/PNS) among patients with progressive supranuclear palsy (PSP)-like manifestations.

METHODS

In this narrative review, we first discuss the clinical characteristics of AE/PNS in comparison to those of PSP, followed by a discussion of diagnosis and treatment.

RESULTS

The antibodies involved in these conditions include anti-IgLON5, -Ma2, and -Ri antibodies, each of which has a characteristic clinical presentation. The steps in the diagnosis of AE/PNS in patients with PSP-like manifestations include (i) suspicion of AE/PNS based on clinical presentations atypical of PSP and (ii) antibody detection measures. Methods used to identify antibodies include a combination of tissue-based assays and confirmatory tests. The primary confirmatory tests include cell-based assays and immunoblotting. Treatments can be divided into immunotherapy and tumor therapies, the former of which includes acute and maintenance therapies.

CONCLUSIONS

One of the major challenges of diagnosis is that existing reports on PSP-like patients with AE/PNS include only case reports, with the majority discussing antibodies other than anti-IgLON5 antibody. As such, more patients need to be evaluated to establish the relationship between antibodies and PSP-like manifestations.

Canine idiopathic generalized tremor syndrome, immune-mediated?

Idiopathic generalized tremor syndrome is a disorder characterized by an acute onset of full-body tremors, sometimes accompanied by vestibulo-cerebellar signs, that is responsive to treatment with corticosteroids. Although considered to have an overall good outcome, relapsing and persistent mild clinical signs have been described. So far, little is known about the etiopathology of this syndrome, but it is believed to have an immune-mediated origin. In human medicine, description of numerous autoantibodies involved in certain non-infectious neurologic disorders has revolutionized understanding of their pathophysiology, diagnosis and treatment. In this multicenter retrospective study, we aimed to describe the clinical signs, course, and outcome of dogs with idiopathic generalized tremor syndrome and correlate potential findings with the presence or absence of autoantibodies associated with autoimmune cerebellar syndromes in humans. Information regarding signalment, history, clinical signs, laboratory findings, diagnostic imaging and testing for regional infectious diseases was gathered and the remaining serum and CSF samples were then analyzed for neural antibodies against targets associated with autoimmune encephalitic diseases of humans. Thirty-three dogs were included, and screening for neural antibodies was performed in 30 of those dogs. The analysis showed an increased titer of mGluR1 antibodies in two dogs, GFAP and later in the course of disease mGluR1 antibodies in one dog and an increase in unspecific autoantibodies which could not be further classified in two dogs. Dogs with detectable neural autoantibodies always had cerebrospinal fluid abnormalities in the form of a pleocytosis, with or without increased protein concentration, and tended to present with hyperthermia, potentially indicating a more severe clinical form of idiopathic generalized tremor syndrome in these cases. In conclusion, idiopathic generalized tremor syndrome is proposed to be an immune-mediated disorder potentially mediated by neural autoantibodies in a subgroup of dogs.

[Autoimmune encephalitis: psychiatric aspects]

Autoimmune encephalitis is a group of diseases researched by both neurologists and psychiatrists. Despite a large number of studies and practical recommendations, the differential diagnosis and early diagnostics still remains an important issue. The most difficult to diagnose are cases that debut as mental disorders and/or occur without neurological symptoms. The literature review presents the current state of the problem with an emphasis on the practice of a psychiatrist.

Therapeutic Plasma Exchange and Multiple Sclerosis Dysregulations: Focus on the Removal of Pathogenic Circulatory Factors and Altering Nerve Growth Factor and Sphingosine-1-Phosphate Plasma Levels

Multiple sclerosis (MS) is predominantly an immune-mediated disease of the central nervous system (CNS) of unknown etiology with a possible genetic predisposition and effect of certain environmental factors. It is generally accepted that the disease begins with an autoimmune inflammatory reaction targeting oligodendrocytes followed by a rapid depletion of their regenerative capacity with subsequent permanent neurodegenerative changes and disability. Recent research highlights the central role of B lymphocytes and the corresponding IgG and IgM autoantibodies in newly forming MS lesions. Thus, their removal along with the modulation of certain bioactive molecules to improve neuroprotection using therapeutic plasma exchange (TPE) becomes of utmost importance. Recently, it has been proposed to determine the levels and precise effects of both beneficial and harmful components in the serum of MS patients undergoing TPE to serve as markers for appropriate TPE protocols. In this review we discuss some relevant examples, focusing on the removal of pathogenic circulating factors and altering the plasma levels of nerve growth factor and sphingosine-1-phosphate by TPE. Altered plasma levels of the reviewed molecular compounds in response to TPE reflect a successful reduction of the pro-inflammatory burden at the expense of an increase in anti-inflammatory potential in the circulatory and CNS compartments.