Pathogenic roles of antiganglioside antibodies in immune-mediated neuropathies

Atypical anti-GQ1b antibody syndrome presenting with vomiting as the initial symptom: a case report and literature review

BACKGROUND

Anti-GQ1b antibody syndrome is a rare autoimmune neuropathy, and atypical cases are even more rare, only a few cases have been reported. Anti-GQ1b antibody syndrome is difficult in early diagnosis and prone to misdiagnosis. Generally,in children with anti-GQ1b antibody syndrome,extraocular muscle paralysis is the initial symptom. However, anti-GQ1b antibody syndrome with vomiting as the initial symptom followed by abnormal gait has not been reported.

CASE PRESENTATION

We reported a case of anti-GQ1b antibody syndrome with vomiting as the initial symptom, followed by abnormal gait. One day after vomiting, the child developed abnormal gait, which primarily manifested as a slight tilt of the upper body during walking as well as an opening and swaying of the legs at fast walking paces,then progressively aggravated, and finally he could not stand on his own.In the auxiliary examination, cerebrospinal fluid routine,biochemical and metagenomic Next-Generation Sequencing (DNA and RNA), brain + spinal cord contrast magnetic resonance imaging (MRI),magnetic Resonance angiography (MRA) and diffusion-weighted image (DWI), hip and knee joint ultrasound showed normal results. Anti-GQ1b antibody syndrome was not confirmed until the positive anti-GQ1b IgG antibody was detected in the serum. After treatment with intravenous immunoglobulin (IVIG) and glucocorticoid, the child recovered well, and a 3-month outpatient follow-up showed that the child was able to walk normally.

CONCLUSIONS

There are no previous reports of anti-GQ1b antibody syndrome with vomiting as the initial symptom, followed by abnormal gait. Therefore, this valuable case contributes to expanding the database of clinical manifestation of anti-GQ1b antibody syndrome, so as to improve pediatricians' awareness about such rare diseases and reduce misdiagnosis.

A Rare Case of Guillain–Barré Syndrome with Signs of Meningeal Irritation and Treatment-Related Fluctuations/Relapse

Guillain–Barré Syndrome is an acute inflammatory demyelinating polyradiculoneuropathy that can present at any age. The presentation of Guillain–Barré syndrome may be variable as the classic symptoms of areflexia and flaccid paralysis may or may not be present. Here we reported a case of a 15-year-old male patient who presented with complaints of weakness in bilateral lower limbs with inability to sit along with slurred speech and drooling of saliva with positive meningeal signs like neck stiffness and Kernig's sign. His symptoms improved with immunoglobulin therapy. Five days later, the child again had pain and increased weakness with increased work of breathing for which repeat dose and course of immunoglobulins were given. As patients with signs of meningeal irritation may suggest other diseases such as meningitis, it is important to consider atypical cases of Guillain–Barré syndrome along with treatment-related fluctuations as observed in our patient.

Pragmatic guide to peripheral nerve disease and the role of clinical biomarkers

In clinical neurology practice, there are few sensitive, specific and responsive serological biomarkers reflecting pathological processes affecting the peripheral nervous system. Instead, we rely on surrogate multimodality biomarkers for diagnosis and management. Correct use and interpretation of the available tests is essential to ensure that appropriate treatments are used and adjusted in a timely fashion. The incorrect application or interpretation of biomarkers can result in misdiagnosis and delays in appropriate treatment. Here, we discuss the uses and limitations of such biomarkers and discuss possible future developments.

A Severe Course of Relapsing-Remitting Acute-Onset Chronic Inflammatory Demyelinating Polyneuropathy in a Young Man

Acute-onset chronic inflammatory demyelinating polyneuropathy (A-CIDP) is an immune mediated neuropathy characterized by progressive weakness and sensory impairment lasting over 2 months. Guillain-Barré-Strohl syndrome (GBS) is an immune mediated polyneuropathy with a similar presentation often over less than 4 weeks. While some have argued for the existence of recurrent GBS, most classify the syndrome as a form of relapsing-remitting CIDP. However, there are cases of GBS with treatment-related fluctuations that must be distinguished from A-CIDP as patients with A-CIDP require long-term immunotherapy. In this case report, we discuss a patient with multiple relapses over 3 years, who is more likely to have A-CIDP. His ganglioside profile, which has rarely been reported in A-CIDP, included high concentrations of anti-GM1, anti-GD1a, and anti-GD1b antibodies, which may account for his severe disease course.

The incidental finding of elevated anti GQ1B antibodies in a patient with selective small fiber neuropathy

Small fiber neuropathy (SFN) selectively affects small diameter sensory and/or autonomic axons. Pain and autonomic dysfunctions are the most common symptoms. SFN occurs in several autoimmune diseases and autoantibodies against neuronal proteins may play a role in SFN pathophysiology. Anti-GQ1b antibody has been associated with Miller Fisher syndrome, Bickerstaff's brainstem encephalitis, acute ophthalmoplegia, pharyngeal-cervical-brachial weakness and peripheral neuropathy involving large fibers. Isolated SFN associated with anti-GQ1b antibodies has not been previously reported. Here we report a 45-year-old woman presenting with highly positive anti-GQ1b titer and selective SFN without central nervous system or peripheral large nerve involvement. She improved upon administration of adalizumab. Further studies will clarify a possible pathogenetic role of antiganglioside antibodies in SFN. Moreover, the recognition of antiganglioside antibodies in SFN may have therapeutic consequences with patients who would benefit from immunotherapy.

Autoantibodies to tetraspanins (CD9, CD81 and CD82) in demyelinating diseases

Tetraspanin family proteins, CD9, CD81 and CD82 are expressed in the oligodendrocytes and Schwann cells. We investigated autoantibodies to tetraspanin proteins in patients with demyelinating diseases. Sera were collected from 119 multiple sclerosis patients, 19 neuromyelitis optica, 42 acute inflammatory demyelinating polyneuropathy, 23 chronic inflammatory demyelinating polyneuropathy and 13 acute motor axonal neuropathy as well as 55 healthy controls. Few multiple sclerosis and acute inflammatory demyelinating polyneuropathy patients had autoantibodies that were weakly reactive to CD9 or CD81 but the significance is unclear. It is unlikely that these autoantibodies are pathogenic or serve as potential biomarkers in demyelinating diseases.

Ambiguous value of anti-ganglioside IgM autoantibodies in Guillain-Barré syndrome and its variants

Anti-ganglioside autoantibodies of the IgG type are detected in a half of patients with Guillain-Barré syndrome (GBS), and their detection strongly supports the diagnosis of GBS. In contrast, anti-ganglioside IgM antibodies are also often detected in GBS patients, but it remains unclear whether IgM antibodies indicate a diagnosis of GBS. We identified four GBS patients (3.3%) who tested positive for IgM antibodies but negative for IgG antibodies among 122 patients with GBS and its variants. These four patients were all adolescents or young adults (age 13-22 years), experienced preceding gastrointestinal symptoms, and had serological and/or bacterial evidence of recent Campylobacter jejuni enteritis. Serum IgG reacted strongly with the lipo-oligosaccharide (LOS) of the C. jejuni isolates from these patients' stool specimens. Thin-layer chromatography with immunostaining showed that their serum IgG reacted with resorcinol-positive portion of LOS, suggesting that these patients had IgG autoantibodies against sialic acid-containing epitopes, probably unrecognized ganglioside-like structures on the bacterial LOS. We also examined anti-ganglioside autoantibodies in 22 patients with C. jejuni enteritis without subsequent neurological disorders and detected IgM antibodies in seven (32%) patients. Our data indicate that anti-ganglioside IgM antibodies can be detected in C. jejuni enteritis without complication of GBS, and that the detection of anti-ganglioside IgM antibodies does not always support a diagnosis of GBS. IgG autoantibodies against unrecognized gangliosides might play a role in the development of disease in patients with GBS in whom only anti-ganglioside IgM antibodies are detected by routine clinical testing.