Molecular recognition and regulation of the lectin pathway of complement activation

Lead Research Organisation: University of Leicester
Department Name: Infection Immunity and Inflammation


The complement system is a fundamental part of the mammalian immune system, neutralising potentially harmful bacteria, viruses and parasites. A relatively poorly understood branch of this system, called the lectin pathway, relies on recognition of carbohydrates on the surfaces of invading microorganisms to initiate the complement cascade. The lectin pathway is particularly important in the early stages of infection, before specific antibodies can be synthesized by the host or when the immune system is suppressed, for example during HIV infection or following chemotherapy. It kills pathogens directly and also stimulates and directs other parts of the immune system to generate an appropriate response. Although the lectin pathway normally has a protective role, under certain conditions, it can cause severe damage to host tissues. For example, lectin pathway dependent complement activation is believed to cause substantial cardiovascular damage following restoration of blood flow following myocardial infarction. In this grant proposal, we aim to develop a better understanding of the lectin pathway of complement activation by studying the way in which the components interact with each other to initiate and regulate the reaction cascade. We have already established methods for producing key elements using recombinant DNA technology, so that their mode of action can be investigated in a systematic way. Using the results from these studies, we plan to develop specific inhibitors to lectin pathway activation. These inhibitors will be useful tools to help us understand the role of the lectin pathway in complex biological processes and will also serve as potential drugs for the treatment of diseases, including heart and kidney disease. An additional goal of this project is to change the properties of components of the lectin pathway so that they bind to carbohydrates that are present on the surfaces of tumour cells but are not normally found on healthy tissues. We will test the abilities of these modified components to stimulate the immune system to neutralize tumour cells. The knowledge provided by our research will be translated to the scientific community through publication in high quality scientific journals and by presentations at international conferences. Our research will be communicated to the general public through the University and Departmental Web pages via the University Press Office. In particular, important discoveries will be published in the bimonthly University newletter and in the Annual Report, which highlights major achievements of the University.

Technical Summary

The goal of the proposed work is to understand how molecular interactions regulate the function of the lectin pathway of complement activation. The results of this study are expected to be of significance to both basic and therapeutic applications. Understanding the fundamental issues of recognition in complement activation has general practical applications in protein engineering and for the design of inhibitors of macromolecular interactions. Biochemical and structural approaches are specifically designed to identify detailed interaction and structural information for MBL-MASP and ficolin-MASP interactions. Based on these studies, short constrained peptide mimics of bioactive protein surfaces will be developed, synthesized and characterized. The peptide mimics will serve as specific inhibitors of lectin-MASP interactions, providing a novel set of reagents to dissect the complex pathways that these proteins mediate. In addition these compounds represent potential first generation therapeutic agents for complement-mediated host damage, including reperfusion damage to myocardium, kidney and other tissues. We also plan to use our knowledge of lectin-carbohydrate interactions to engineer novel lectin-specificities into the framework of MBL and ficolins, thereby altering target specificity whilst retaining the ability to activate complement and stimulate the host?s immune system. By targeting sugars commonly found on tumour cells but rarely associated with healthy cells, we aim to develop a range of immunologically active reagents that are selective for diseased tissues.


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Almitairi JOM (2018) Reply to Mortensen et al.: The zymogen form of complement component C1. in Proceedings of the National Academy of Sciences of the United States of America

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Almitairi JOM (2018) Structure of the C1r-C1s interaction of the C1 complex of complement activation. in Proceedings of the National Academy of Sciences of the United States of America

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Asgari E (2014) Mannan-binding lectin-associated serine protease 2 is critical for the development of renal ischemia reperfusion injury and mediates tissue injury in the absence of complement C4. in FASEB journal : official publication of the Federation of American Societies for Experimental Biology

Description Equipment grant
Amount £150,000 (GBP)
Organisation Wellcome Trust 
Sector Charity/Non Profit
Country United Kingdom
Start 06/2009 
End 06/2010
Description MRC Project Grant
Amount £600,000 (GBP)
Organisation Medical Research Council (MRC) 
Sector Academic/University
Country United Kingdom
Start 06/2009 
End 06/2012
Description MRC project grant
Amount £532,558 (GBP)
Funding ID MR/K011715/1 
Organisation Medical Research Council (MRC) 
Sector Academic/University
Country United Kingdom
Start 01/2013 
End 12/2015
Description MRC project grant
Amount £438,792 (GBP)
Organisation Medical Research Council (MRC) 
Sector Academic/University
Country United Kingdom
Start 02/2011 
End 06/2013
Description VIP Fellowship
Amount £55,000 (GBP)
Organisation Wellcome Trust 
Sector Charity/Non Profit
Country United Kingdom
Start 09/2008 
End 09/2009
Title Recombinant C1q 
Description We have recently generated a recombinant form of human C1q, the first component of the classical pathway of complement, by co-expressing the three polypeptide chains, from which it is assembled, in a Chinese hamster ovary cell line. This has not been achieved before despite considerable efforts by us (as well as other research groups throughout the world), and is a major breakthrough. It will enable detailed study of the many important physiological roles of C1q within maintenance of human and animal health and will also facilitate understanding of the contribution of C1q to disease progression, e.g. the role of C1q in inflammatory diseases such as rheumatoid arthritis and lupus erythmatosus. 
Type Of Material Technology assay or reagent 
Year Produced 2012 
Provided To Others? Yes  
Impact The reagent was only developed recently (within the last six months), so there has not been sufficient time to exploit its benefits fully. However, we confidently predict that it will become a widely used resourse, both by us and other researchers worldwide, to study the role of C1q in health and disease, using in vitro and in vivo approaches. 
Description Molecular characterization of a novel chitin receptor FIBCD-1 
Organisation University of Southern Denmark
Department Medical Biotechnology Center Southern Denmark
Country Denmark 
Sector Academic/University 
PI Contribution CHaracterization of FIBCD-1 using biophysical methods (analytical ultracentrifugation)
Collaborator Contribution Identification and preliminary characterization of a novel ficolin-like receptor
Impact 19892701
Start Year 2007
Description Molecular interactions in the immune system 
Organisation University of Warwick
Department Warwick Medical School
Country United Kingdom 
Sector Academic/University 
PI Contribution Characterization of interactions of MBL with MASPs, ficolins with MASPs and C1q with C1r and C1s
Collaborator Contribution Molecular characterization using Proteon XPR36 system
Impact 18831010, 20932025, 20674073, 20118239
Start Year 2006
Description Role of MBL and C1q in brain function 
Organisation Helmholtz Association of German Research Centres
Department The Max Delbrück Center for Molecular Medicine (MDC)
Country Germany 
Sector Academic/University 
PI Contribution Supply purified rat C1q and purified recombinant MBL for studies on microglial cells
Collaborator Contribution Using our recombinant proteins to study microglial function
Impact 18831010
Start Year 2006
Title Inhibition of MASP using small molecule inhibitors 
Description Target for MBL-MASP inhibition by small molecule inhibitors 
IP Reference US2012225437 
Protection Patent granted
Year Protection Granted 2012
Licensed Yes
Impact Work in progess
Description School work experience 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact We have hosted a number (6 in total; 2 per year) of work experience students from local schools and colleges for 1 or 2 week periods. During this time, we explained our research , showed the students how to work safely in the laboratory and helped them to contribute towards our research e.g. through setting up PCR reactions, running gels and assisting in basic laboratory work. In one case, a student was keen to return to the lab to work during the summer holidays (between the lower and upper 6th form). In recognition of his contribution, the student will be a named author in an MRC-funded manuscript which will be submitted for publication in the coming year.

Work contributed by one of the students will be sumitted for publication in 2010.
Year(s) Of Engagement Activity 2006,2007,2008,2009,2010