Control of neutrophil infiltration into inflamed tissue. the role of μ-calpain in neutrophil shape change

Lewis, Kimberley Jane 2011. Control of neutrophil infiltration into inflamed tissue. the role of μ-calpain in neutrophil shape change. PhD Thesis, Cardiff University.

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Abstract

Neutrophil spreading is an essential process in neutrophil extravasation and is a key step in the process of inflammation. Inhibition of neutrophil spreading is therefore a potential therapeutic target for the treatment of inflammatory diseases. Resting neutrophils have wrinkles in their plasma membrane which are held in place by cytoskeletal elements which act as a 'molecular velcro'. These proteins may be cleaved by cytosolic proteases such as the Ca2+-activated protease u calpain which contains a 'C2 like' domain. Calpain activation is also implicated in the expansion of the membrane during phagocytosis. The primary challenge over the course of this project was expressing of fluorescent proteins in myeloid cells. In this thesis I show that lentiviral transduction was the most efficient method for the stable transfection of myeloid cell lines. Fluorescent-C2 domain translocates to the plasma membrane during experimental Ca2+ influx and during phagocytosis. A similar mechanism may occur in human neutrophils as μ-calpain is located at the plasma membrane in activated human neutrophils. I also found that neutrophils may have a mechanism of retrieving excess membrane from the phagosome after phagocytosis. The work presented here has shown that by virtue of its 'C2 like' domain μ-calpain could translocate to the plasma membrane during the calcium influx which accompanies neutrophil spreading, μcalpain was shown to be present in the right place and at the right time in primary human neutrophils during neutrophil shape change and thus may play a key role in allowing the unwrinkling of the neutrophil membrane. Inhibition of calpain activity inhibits neutrophil spreading and therefore calpain poses a potential target for the treatment of inflammatory diseases.

Item Type:	Thesis (PhD)
Status:	Unpublished
Schools:	Medicine
Subjects:	R Medicine > R Medicine (General)
ISBN:	9781303196744
Date of First Compliant Deposit:	30 March 2016
Last Modified:	19 Mar 2016 23:30
URI:	https://orca.cardiff.ac.uk/id/eprint/54485

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