Mechanisms of neutrophil-mediated immune defense and their role in inflammation and autoimmune disease.

Lead Research Organisation: MRC National Inst for Medical Research

Abstract

Multicellular organisms evolved sophisticated immune systems to protect themselves against infection. We are interested in understanding how our immune system regulates its responses to microbial challenges. We focus on specialized antimicrobial cells known as neutrophils, since these play central microbicidal and regulatory roles during the course of infection. We are trying to understand the mechanisms that allow these cells become activated and kill a variety of different microbes.
We are focusing our attention on the mechanism that allows these cells to release large web like structures that capture and kill bacteria and fungi. These NETs, as they are called, are thought to protect against infection but are also thought to trigger autoimmunity. We plan to investigate the role of NETs in autoimmune disease. We are exploring whether NETs play a detrimental role in inflammatory disease and sepsis.

Technical Summary

Microbial infection is a major health issue and a major cause of death worldwide. We are particularly interested in uncovering novel mechanisms of immune defense against microbial infection. We focus on neutrophils as these antimicrobial phagocytes are amongst the first immune cells to populate the sites of infection in great numbers, can shape the immune response and play essential roles in microbial clearance.

Neutrophils employ a novel strategy to combat infection as they die to release extracellular web-like structures known as neutrophil extracellular traps (NETs) that trap and kill a variety of pathogens (Fig. 1A). We are investigating the molecular mechanism that regulates NET release, the subsequent role of NETs in mediating immune defense, their role during sepsis and their implication in triggering autoimmune and autoinflammatory disease (Fig. 1B).

Mechanism of translocation of neutrophil elastase during NET formation

More specifically, we have demonstrated that during NET formation, neutrophil elastase (NE) selectively escapes from its storage granules and translocates to the nucleus where it partially cleaves core histones (Fig. 1C). The molecular events underlying this crucial step remain unclear. Recently, we have identified an upstream mediator of NE translocation and have shown that this factor mediates the permeabilization of the granular membrane and the release of NE in a ROS dependent manner (unpublished).

Mechanism of regulation of antimicrobial proteases

A fundamental and often controversial question in neutrophil biology that has yet to be addressed is how are antimicrobial proteins regulated in order to prevent cytotoxicity and autodegradation during the resting state. Our studies of NET formation revealed that the translocation of NE requires its protease activity. Within the context of these studies we are investigating the molecular mechanisms employed by reactive oxygen species to activate antimicrobial proteins. Notably, our recent studies have uncovered a complex that appears to regulate the neutrophil’s potent proteases (unpublished). We are in the process of characterizing this phenomenon.

What are the external upstream signals and neutrophil surface molecules that regulate NET formation

In addition, we would like to understand the external cues that instruct neutrophils as to how to respond appropriately during an infection. In particular, the upstream signals that regulate NET formation are not known. It is also unclear why certain microbes induce NET formation better than others. Moreover, we are interested in understanding how these early neutrophil responses shape the subsequent innate and adaptive immunity. Notably, degranulation and more effectively NET formation lead to the release of molecules with potent immunomodulatory properties whose role has not been thoroughly investigated. We plan to identify and analyse these stimuli in the context of infection with specific pathogens.
 
Description Influence on Clinical practices to treat human patients
Geographic Reach Multiple continents/international 
Policy Influence Type Influenced training of practitioners or researchers
Impact Our work has revealed the important role of neutrophil extracellular traps in immunocompromised individuals and cycstic fibrosis patients. Our findings have contributed to gene therapy treatments for Chronic Granulomatous Disease patients. We have also provided guidelines and direct targets for therapeutic intervention to treat Cystic fibrosis. We are continuing this work with autoimmune disease patients.
 
Description Neutrophils and Atherosclerosis - Professor Qingbo Xu 
Organisation King's College London
Department BHF Centre of Research Excellence
Country United Kingdom 
Sector Academic/University 
PI Contribution We are the primary partners in this collaboration. We are investigating the role of neutrophils in atherosclerosis.
Collaborator Contribution Professor Xu provided us with ApoE deficient animals, technical training and advice and will participate in sample analysis for experiments with in vivo models that we are conducting.
Impact We aim to obtain the first data form the collaborative part of the of this project in early 2014
Start Year 2013
 
Description Regulation of NETosis - Professor Gordon Brown 
Organisation University of Aberdeen
Department Aberdeen Fungal Group
Country United Kingdom 
Sector Academic/University 
PI Contribution We are the major partner in this collaboration where we are investigating the molecular mechanisms regulating decision making in neutrophils
Collaborator Contribution Dr Brown's laboratory provides us with Dectin-1 deficient mice and also performs infections to generate samples that we analyze.
Impact We are close to writing up the first publication from this collaboration.
Start Year 2012
 
Description Role of neutrophil extracellular traps in autoimmune disease 
Organisation St Thomas' Hospital
Department Rayne Institute, St Thomas' Hospital
Country United Kingdom 
Sector Academic/University 
PI Contribution We are conducting preliminary studies with primary cells from human patients to examine a whether a novel mechanism regulating the formation of neutrophil extracellular traps is implicated in autoimmune disease.
Collaborator Contribution Our partner is providing human blood from the patient cohorts they are treating
Impact Still preliminary at this stage
Start Year 2013
 
Description 2012 Wright-Fleming Institute Seminar series, Imperial 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Type Of Presentation Keynote/Invited Speaker
Geographic Reach Regional
Primary Audience Health professionals
Results and Impact "Neutrophil Extracellular traps in Immunity and Disease"

Wright-Fleming Seminars
Infection and Immunity Seminar Series
June 24, 2013

I was invited to present in front of other researchers and medical doctors who are interested and work on the role of the innate immune system in infectious and inflammatory diseases.

There was great interested followed by a very lengthy discussion after the seminar. Being the an expert in this field I also advised several groups on setting up related projects.
Year(s) Of Engagement Activity 2013
URL http://www1.imperial.ac.uk/medicine/about/institutes/wfi/wfseminars/
 
Description 2013, Infection and Immunity seminar series. University of York 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Type Of Presentation Keynote/Invited Speaker
Geographic Reach Regional
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact "Neutrophil extracellular traps in Immunity and Disease"

Nov 28, 2013

Will take place in a couple of weeks.
Year(s) Of Engagement Activity 2013
 
Description 2013, Mill Hill Lecture 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Type Of Presentation Keynote/Invited Speaker
Geographic Reach Local
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact Decision making in neutrophil antimicrobial responses

18 Sept., 2013

My first Institute-wide lecture where I presented an overview of the work i the lab and new projects, was very well received by a packed audience.

I received very positive feedback from peers across different disciplines.
Year(s) Of Engagement Activity 2013
 
Description 2014 British Society for Immunology seminar series, Aberdeen 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach Regional
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact "Decision making in neutrophil antimicrobial responses"

23 Oct 2014

Will take place next month
Year(s) Of Engagement Activity 2014
 
Description March 5, 2014 Spring Immunology Schoo, Ettal, Germany. German Society of immunologists. 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Presented a seminar on neutrophils and recent research and coached delegates in 5 day immunology course for PhD students and postdocs and world class group leaders in immunology. We work on a new and hot field and the talk sparked much excitement.

Educational impact on colleagues
Year(s) Of Engagement Activity 2014
URL https://www.dgfi.org/content/spring-school-overview
 
Description Naito Annual conference invited speaker Japan 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Type Of Presentation Keynote/Invited Speaker
Geographic Reach International
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact Oct 21, 2012. 34th Naito Conference on Infection Immunity and their Control for Health, Sapporo, Japan.

Neutrophil extracellular traps in immunity and disease

I gave the opening lecture and co-chaired the Host Immunity section.

I had the opportunity to present an overview of the field of neutrophil extracellular traps (NETs) and exciting unpublished data over the mechanism of NET formation. The talk was very well received and gave me the opportunity to clarify address several important questions by our international colleagues.
Year(s) Of Engagement Activity 2012
URL http://naito.umin.jp/html/034/pdf/program-34th_NaitoConf.pdf
 
Description Seminar Radical Society Conference London 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Type Of Presentation Keynote/Invited Speaker
Geographic Reach International
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact Keynote lecture on innate immunity session in front of a large international audience of principal investigators and post docs.

"Neutrophil extracellular traps in Immunity and Disease"
Sept 7, 2012, Imperial College, London,

The talk generated great interest as we are the founders of a new and exploding field in infection biology.
Year(s) Of Engagement Activity 2012
 
Description Talk at the Kennedy Institute of Rheumatology, Imperial College, London 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Type Of Presentation Keynote/Invited Speaker
Geographic Reach Regional
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact "Neutrophil extracellular traps in immunity and disease"

Nov 12, 2012. Kennedy Institute of Rheumatology, Imperial College, London.

Invited speaker.
The talk was extremely well received as the audience was very interested int he field of NETs. I had the opportunity to give expert advice on several projects running at the Institute.

My visit there lead to the establishment of a new collaboration.
Year(s) Of Engagement Activity 2012