Anti-CNTN1 IgG3 induces acute conduction block and motor deficits in a passive transfer rat model

Background

Autoantibodies against the paranodal protein contactin-1 have recently been described in patients with severe acute-onset autoimmune neuropathies and mainly belong to the IgG4 subclass that does not activate complement. IgG3 anti-contactin-1 autoantibodies are rare, but have been detected during the acute onset of disease in some cases. There is evidence that anti-contactin-1 prevents adhesive interaction, and chronic exposure to anti-contactin-1 IgG4 leads to structural changes at the nodes accompanied by neuropathic symptoms. However, the pathomechanism of acute onset of disease and the pathogenic role of IgG3 anti-contactin-1 is largely unknown.

Methods

In the present study, we aimed to model acute autoantibody exposure by intraneural injection of IgG of patients with anti-contacin-1 autoantibodies to Lewis rats. Patient IgG obtained during acute onset of disease (IgG3 predominant) and IgG from the chronic phase of disease (IgG4 predominant) were studied in comparison.

Results

Conduction blocks were measured in rats injected with the “acute” IgG more often than after injection of “chronic” IgG (83.3% versus 35%) and proved to be reversible within a week after injection. Impaired nerve conduction was accompanied by motor deficits in rats after injection of the “acute” IgG but only minor structural changes of the nodes. Paranodal complement deposition was detected after injection of the “acute IgG”. We did not detect any inflammatory infiltrates, arguing against an inflammatory cascade as cause of damage to the nerve. We also did not observe dispersion of paranodal proteins or sodium channels to the juxtaparanodes as seen in patients after chronic exposure to anti-contactin-1.

Conclusions

Our data suggest that anti-contactin-1 IgG3 induces an acute conduction block that is most probably mediated by autoantibody binding and subsequent complement deposition and may account for acute onset of disease in these patients. This supports the notion of anti-contactin-1-associated neuropathy as a paranodopathy with the nodes of Ranvier as the site of pathogenesis.

Electronic supplementary material

The online version of this article (10.1186/s12974-019-1462-z) contains supplementary material, which is available to authorized users.

Update on cardiac imaging techniques 2012

Cardiac imaging is one of the basic pillars of modern cardiology. The potential list of scenarios where cardiac imaging techniques can provide relevant information is simply endless so it is impossible to include all relevant new features of cardiac imaging published in the literature in 2012 in the limited format of a single article. We summarize the year's most relevant news on cardiac imaging, highlighting the ongoing development of myocardial deformation and 3-dimensional echocardiography techniques and the increasing use of magnetic resonance imaging and computed tomography in daily clinical practice.

Factors predicting long-term mortality in patients with hypertrophic cardiomyopathy

OBJECTIVES

In this study, we aimed to elucidate the factors affecting long-term all-cause mortality in patients with hypertrophic cardiomyopathy (HCM).

METHOD

We retrospectively examined 31 patients (22 males and 9 females) diagnosed with HCM from 1999 to 2013. All subjects had sinus rhythm at the time of evaluation. Four patients had history of paroxysmal atrial fibrillation (PAF). In addition to echocardiographic examination plasma angiotensin-converting enzyme (ACE) activity and gene polymorphism were determined. The variables that were found to be significant in mortality were then included in multivariate analysis.

RESULTS

At the final follow-up examination, 12 patients had died, including 2 due to congestive heart failure and 10 due to sudden cardiac death. Patients with PAF had significantly higher mortality (P = 0.008). Moreover, left ventricular (LV) end-diastolic diameter (P = 0.04), LV systolic diameter (P = 0.001), LV mass index (P = 0.01), and left atrium diameter (P = 0.003) were found to be significantly correlated with mortality. However, no significant correlation was noted between mortality and age, type of HCM (familial/nonfamilial and obstructive/nonobstructive), ACE gene polymorphism, and plasma ACE level. In the multivariate analysis, left atrial (LA) diameter was still significantly associated with mortality. The LA diameter with a cutoff value of 4.1 cm predicted 13-year mortality with a sensitivity of 82% and specificity of 78%.

CONCLUSION

Instead of the ACE genotype and activity, echocardiographic evaluation findings such as LV systolic and diastolic diameters, LV mass index, and particularly LA dimension may predict long-term mortality in patients with HCM. PAF has also significant importance in the long-term mortality in patients with HCM.

Myocardial perfusion abnormality in the area of ventricular septum-free wall junction and cardiovascular events in nonobstructive hypertrophic cardiomyopathy

Myocardial perfusion abnormality in the left ventricle is known to be prognostic in patients with hypertrophic cardiomyopathy (HCM). Magnetic resonance imaging and necropsy studies on HCM hearts revealed myocardial lesions predominating in the area of ventricular septum-free wall junction. We assessed perfusion abnormality in this area and correlated it with the prognosis of HCM patients. We performed exercise Tc-99m tetrofosmin myocardial scintigraphy in 55 patients with nonobstructive HCM. Perfusion abnormalities were semiquantified using a 5-point scoring system in small areas of anterior junctions of basal, mid, and apical short axis views in addition to a conventional 17-segment model. All patients were prospectively followed for sudden death, cardiovascular death and hospitalization for heart failure or stroke associated with atrial fibrillation. Cardiovascular events occurred in 10 patients during an average follow-up period of 5.7 years. Stress and rest scores from anterior junction, and conventional summed stress score were significantly higher in patients with cardiovascular events than without (all P < 0.05). Anterior junction stress score of >2 produced a sensitivity of 50% and a specificity of 98% for cardiovascular events and was an independent predictor (hazard ratio 8.33; 95% confidence interval, 1.61-43.5; P = 0.01), with rest scores producing similar values, which were higher than summed stress score of >8 (5.68; 1.23-26.3; P = 0.03). The absence of myocardial perfusion abnormality in the narrow area of anterior junction differentiated HCM patients with low-risk.