Septin-5 and -7-IgGs: Neurologic, Serologic, and Pathophysiologic Characteristics

BACKGROUND AND OBJECTIVES

We sought to determine clinical significance of neuronal septin autoimmunity and evaluate for potential IgG effects.

METHODS

Septin-IgGs were detected by indirect immunofluorescence assays (IFAs; mouse tissue and cell based) or Western blot. IgG binding to (and internalization of) extracellular septin epitopes were evaluated for by live rat hippocampal neuron assay. The impact of purified patient IgGs on murine cortical neuron function was determined by recording extracellular field potentials in a multielectrode array platform.

RESULTS

Septin-IgGs were identified in 23 patients. All 8 patients with septin-5-IgG detected had cerebellar ataxia, and 7 had prominent eye movement disorders. One of 2 patients with co-existing septin-7-IgG had additional psychiatric phenotype (apathy, emotional blunting, and poor insight). Fifteen patients had septin-7 autoimmunity, without septin-5-IgG detected. Disorders included encephalopathy (11; 2 patients with accompanying myelopathy, and 2 were relapsing), myelopathy (3), and episodic ataxia (1). Psychiatric symptoms (≥1 of agitation, apathy, catatonia, disorganized thinking, and paranoia) were prominent in 6 of 11 patients with encephalopathic symptoms. Eight of 10 patients with data available (from 23 total) improved after immunotherapy, and a further 2 patients improved spontaneously. Staining of plasma membranes of live hippocampal neurons produced by patient IgGs (subclasses 1 and 2) colocalized with pre- and post-synaptic markers. Decreased spiking and bursting behavior in mixed cultures of murine glutamatergic and GABAergic cortical neurons produced by patient IgGs were attributable to neither antigenic crosslinking and internalization nor complement activation.

INTERPRETATION

Septin-IgGs are predictive of distinct treatment-responsive autoimmune central nervous system (CNS) disorders. Live neuron binding and induced electrophysiologic effects by patient IgGs may support septin-specific pathophysiology. ANN NEUROL 2022;92:1090-1101.

[Corrigendum] Overexpression of septin‑7 inhibits melatonin‑induced cell apoptosis in human fetal osteoblastic cells via suppression of endoplasmic reticulum stress

Subsequently to the publication of this paper, an interested reader drew to the authors' attention that Figs. 2 and 4, featured on p. 4820 and 4821 respectively, contained apparently matching control β‑actin western blots. The authors have consulted their original data, and realized that the control western blot images were inadvertently selected incorrectly for Fig. 2. The corrected version of Fig. 2, showing the relevant β‑actin bands for Fig. 2, is shown on the next page. Note that the errors in Fig. 2 did not significantly affect the results or the conclusions reported in this paper, and all the authors agree to this Corrigendum. The authors are grateful to the Editor of Molecular Medicine Reports for allowing them the opportunity to publish this corrigendum, and apologize to the readership for any inconvenience caused. [the original article was published in Molecular Medicine Reports 17: 4817‑4822, 2018; DOI: 10.3892/mmr.2018.8449].

Overexpression of septin-7 inhibits melatonin-induced cell apoptosis in human fetal osteoblastic cells via suppression of endoplasmic reticulum stress

Our previous study demonstrated that melatonin could induce apoptosis in the human fetal osteoblastic (hFOB) 1.19 cell line via induction of endoplasmic reticulum stress (ERS), and recent studies have demonstrated that the expression of septin‑7 (SEPT7) exhibits a positive correlation with the concentration of melatonin. Western blotting demonstrated the expression level of SEPT7 was significantly upregulated in a dose‑dependent manner following treatment with differing concentrations of melatonin compared with the control groups, which did not receive any treatment. The expression of proteins associated with cell apoptosis and endoplasmic reticulum stress (ERS; pro-caspase‑3, cleaved caspase‑3, C/EBP‑homologous protein, 78 kDa glucose‑regulated protein and phosphorylated‑eukaryotic translation initiation factor 2α) were decreased following transfection with SEPT7 overexpression plasmid and increased following transfection with SEPT7 small interfering RNA compared with the control groups. The results of the present study suggest that SEPT7 inhibits melatonin‑induced cell apoptosis via suppression of ERS.