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01.12.2016 | Research | Ausgabe 1/2016 Open Access

Journal of Neuroinflammation 1/2016

Complement system activation contributes to the ependymal damage induced by microbial neuraminidase

Zeitschrift:
Journal of Neuroinflammation > Ausgabe 1/2016
Autoren:
Pablo Granados-Durán, María Dolores López-Ávalos, Timothy R. Hughes, Krista Johnson, B. Paul Morgan, Paul P. Tamburini, Pedro Fernández-Llebrez, Jesús M. Grondona
Wichtige Hinweise

Competing interests

Paul P. Tamburini declare that he is a paid employee of Alexion Pharmaceuticals Inc. and owns shares of stock in Alexion Pharmaceuticals Inc. He is an inventor on various patents assigned to Alexion although he do not directly benefit from them financially. The other authors have declared that no other competing interests exist.

Authors’ contributions

MDLA, BPM, PFLL, and JMG conceived and designed the study. PGD, TRH, KJ, and PPT performed the experiments. PGD, MDLA, PFLL, and JMG analyzed the data. PGD, MDLA, and JMG wrote the manuscript. All authors read and approved the final manuscript.

Abstract

Background

In the rat brain, a single intracerebroventricular injection of neuraminidase from Clostridium perfringens induces ependymal detachment and death. This injury occurs before the infiltration of inflammatory blood cells; some reports implicate the complement system as a cause of these injuries. Here, we set out to test the role of complement.

Methods

The assembly of the complement membrane attack complex on the ependymal epithelium of rats injected with neuraminidase was analyzed by immunohistochemistry. Complement activation, triggered by neuraminidase, and the participation of different activation pathways were analyzed by Western blot. In vitro studies used primary cultures of ependymal cells and explants of the septal ventricular wall. In these models, ependymal cells were exposed to neuraminidase in the presence or absence of complement, and their viability was assessed by observing beating of cilia or by trypan blue staining. The role of complement in ependymal damage induced by neuraminidase was analyzed in vivo in two rat models of complement blockade: systemic inhibition of C5 by using a function blocking antibody and testing in C6-deficient rats.

Results

The complement membrane attack complex immunolocalized on the ependymal surface in rats injected intracerebroventricularly with neuraminidase. C3 activation fragments were found in serum and cerebrospinal fluid of rats treated with neuraminidase, suggesting that neuraminidase itself activates complement. In ventricular wall explants and isolated ependymal cells, treatment with neuraminidase alone induced ependymal cell death; however, the addition of complement caused increased cell death and disorganization of the ependymal epithelium. In rats treated with anti-C5 and in C6-deficient rats, intracerebroventricular injection of neuraminidase provoked reduced ependymal alterations compared to non-treated or control rats. Immunohistochemistry confirmed the absence of membrane attack complex on the ependymal surfaces of neuraminidase-exposed rats treated with anti-C5 or deficient in C6.

Conclusions

These results demonstrate that the complement system contributes to ependymal damage and death caused by neuraminidase. However, neuraminidase alone can induce moderate ependymal damage without the aid of complement.
Literatur
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