Determining the effects of ageing on the innate mucosal immune system

Lead Research Organisation: University of Edinburgh
Department Name: The Roslin Institute

Abstract

The mucosal immune system in the intestine plays an important role in protection against food-borne and inhaled pathogens and their toxins. Over 26% of the UK population is >65 years old and this is expected to rise significantly in future decades. The immune response in the intestine and respiratory tract is significantly affected by ageing, a process termed 'immunosenescence'. Although many studies have addressed the age-related changes to systemic immune responses such as those in the spleen and the thymus, the mucosal immune system has received little attention. As a consequence, the mechanisms underlying the decline in immune function in the intestines of the elderly are poorly understood. The significant age-related increases in the incidence and severity of intestinal infections, cancer, inflammatory diseases, coupled with decreases in the efficacy of vaccinations, illustrate the importance of studies aimed at understanding the factors involved in this immunosenescence. Indeed, mortality from intestinal pathogens is substantially increased in the elderly. Similarly the respiratory pathogens influenza virus and Streptococcus pneumoniae also cause significant morbidity and mortality in the elderly, and vaccinations against them are much less effective in the elderly. Improving protective measures in the elderly is also a major public health priority for the World Health Organisation. A specific type of antibody molecules are secreted in the intestine (secretory IgA) and help to protect the intestine against bacterial toxins and infection by pathogenic microorganisms. The ageing-associated decline in the intestinal immune response impairs the IgA response in the intestine. However, the precise stages, cells and molecules within the mucosal immune system that are affected by ageing are not known. The research described in this proposal aims to study in detail the effects of host age on the status and function of the mucosal immune system in both the small and large intestines.
A special type of cells in the lining of the intestine (the epithelium) known as M cells, are specialised to sample the contents of intestine to allow the mucosal immune system to generate an appropriate immune response to the pathogens or toxins within in. In the absence of M cells, mucosal immune responses are less effective. Despite the important role of M cells in mucosal immunity, nothing was known about the effects of aging on their function. Our novel findings show that the function of M cells in the intestines of aged animals is dramatically reduced, significantly impeding their ability to sample the contents of the intestine. We also have evidence that these cells are adversely affected in the mucosal immune system of the upper respiratory tract. These data reveal an important, previously unrecognised, aging-related defect in the mucosal immune system's ability to monitor for ingested and inhaled pathogens. The ageing-associated decline in immune function means that vaccines are less effective in the elderly. The identification of the precise cellular and molecular factors affected in the ageing mucosal immune system is therefore crucial for the development of mucosal vaccines and effective strategies to improve intestinal immunity in aged animals and humans. Therefore, in this study we aim to fully characterise the effects of aging on M cells, identify the molecular and cellular factors which underlie such effects, and explore potential approaches to enhance M-cell maturation and mucosal immune responses in elderly animals and humans. Identification of the factors which cause immunosenescence is crucial for the development of mucosal vaccines to improve immunity in elderly animals and humans, which will ultimately reduce mortality, morbidity and the reliance on antibiotics to treat certain important bacterial infections.

Technical Summary

Antigen (Ag) transcytosis across the follicle-associated epithelium (FAE) of Peyer's patches by cells (M cells) is an important first step in the induction of an efficient mucosal immune response. Furthermore, the targeted delivery of vaccine Ag to M cells is an effective way of inducing a specific immune response. Despite the important role of M cells in mucosal immunity, it was not known of how aging affected their function. Our data show that M-cell density in the gut-associated and nasopharyngeal-associated lymphoid tissues of aged mice is dramatically reduced, and impedes the sampling of gut lumenal Ag. Our data reveal an important, previously unrecognised, aging-related defect in the mucosal immune system's ability to sample ingested and inhaled Ag. A thorough analysis of the cellular and molecular mechanisms that underpin the dramatic aging-related decline in the functional maturation of M cells is crucial to aid our understanding of the factors that influence susceptibility to mucosally-acquired pathogens and identify novel approaches to stimulate M-cell differentiation and improve mucosal immunity in the elderly. Using a mouse model, an integrative approach will be used to fully characterise the effects of aging on M cells, identify the molecular and cellular factors which underlie such effects, and explore potential approaches to enhance M-cell maturation in the elderly. Furthermore, we will test the hypothesis that the effects of aging on M cells impair the induction of Ag-specific mucosal immune responses. To do so, the following objectives will be studied:
Objective 1: Determine the effects of aging on the GALT and NALT
Objective 2: Determine the effects of aging on Ag transcytosis across mucosal epithelia
Objective 3: Determine the effects of aging on the induction of Ag-specific IgA responses
Objective 4: Determine the stroma/lymphocyte-derived factors responsible
Objective 5: Determine the effects of aging on the epithelium-microbiota cross-talk

Planned Impact

Many scientists will significantly benefit from the novel data generated from this proposal which addresses important gaps in our understanding of the effects of aging on the mucosal immune system. Scientist working in the aging field will benefit from having access to the extremely useful resource of a range of tissues, tissue fluid, cells, DNA/RNA samples from a large number of aged mice (2 thru to 18 mo. old) generated from this project. In order to faciltate this, samples and data sets will be made available to interested scientists, for example, via the BBSRC-supported Shared Ageing Research Models portal and bio-bank (www.sharmuk.org).

Researchers in industry and in academia will also benefit from data derived from this project describing the effects of aging on the uptake of mucosal antigens. The targeting of vaccine antigens to M cells is an efficient way of inducing antigen-specific IgA responses. Data describing the influence of aging on the maturation and function of M cells in both the GALT and NALT will aid the design of novel therapeutics, especially those which improve the efficacy of vaccines in the elderly.

UK policy makers will have interest in the project's data on an important gap in our knowledge of the effects of aging on the mucosal immune system. This may influence their assessments on the efficacy of vaccines in the elderly, or susceptibility to important pathogens (eg: Salmonella, influenza). Indeed, the applicant's recent study describing the effects of aging on TSE susceptibility (Brown et al. 2009 J. Immunol. 183, 5199) was discussed by the UK Spongiform Encephalopathies Advisory Committee. Improved vaccine efficacy in the elderly will ultimately lead to a reduction in the use of antibiotics in this population.

Pharmaceutical/vaccine companies will have interest in outputs from this study. During the project the applicant will consult with the Institute's Business Development and Commercialisation Department to seek potential Industry partners to exploit the project's data.

This study will enable the scientists working on the project to acquire many transferable skills in two major disciplines: in vivo immunology and aging. The scientist will also develop import skills in in vivo biology (a currently recognised research priority) and high resolution bioimaging, transcriptomics and bioinformatics. This is a collaborative. Thus, the scientist will gain opportunities to develop their team-working, networking and collaboration skills. The scientist will have many opportunities to present data at external meetings.

Data from this study will be disseminated to the international scientific community using a combination of publication in quality peer-reviewed journals and presentation at scientific meetings eg: international and national scientific conferences, seminars at other research institutions and lectures to undergraduate students. Dr. Mabbott is regularly invited to present data at these events. Eg: he was invited to present his data at last year's BBSRC-sponsored Symposium on 'Ageing: intestine, immunity, microbiota and diet', and chaired The Immunology of Ageing 2014 meeting. Dr. Mabbott is keen to explore opportunities to communicate data from this project to the public through events such as the "Doors Open" day held annually at the Institute, and also his activities as a BBSRC-funded Schools Regional Champion. The release of potential news-worthy publications will be discussed with the Institute and BBSRC press officers and press releases issued when appropriate, as recent examples show: Dr Mabbott's recent study on the effects of aging on BSE transmission (Brown J Gen Virol 2014) received media interest; Data from BBSRC grant (BB/526471/1; McCulloch 2011 PLoS Pathogens) were also featured in the media, on the BBSRC website and in BBSRC Business; Our study on the effects of Salmonella on M cells (Tahoun 2012 Cell Host & Microbe) was also featured by the media and BBSRC.

Publications

10 25 50
 
Description This project had 4 main objectives. The outcomes of these objectives are briefly summarized below. As this has been a study of the effects of ageing on the mouse intestine, these studies were very long in duration. Mice had to be aged to approx. 600 d old before analysis. At the time of writing (March 2019), data from this project were being prepared for publication.

Objective 1: The aim of this objective was to obtain a thorough understanding of the effects of ageing on M cells. We have obtained a detailed time-course of the influence of ageing on M cell development. This large data set can now be used to help determine when and why M cell differentiation is impaired during ageing. From this objective we also compared gene expression in aged and young gut epithelium by mRNA-seq. This objective has created a comprehensive data set which can be used to study in detail the effects of ageing on the gut epithelium.

Objective 2: The aim of this objective was to determine whether ageing affected the sampling of particulate antigens across the gut epithelium. Our data clearly show that aged mice have a highly significantly reduced ability to sample particulate antigens from the gut lumen when compared to young mice. Our data also show a significant correlation between M-cell abundance in the gut epithelium and the ability to sample particulate antigens.

Objective 3: The sampling of particles in the intestine by M cells is important the body to be able to make protective antibodies (IgA) to orally-acquired pathogens. The aim of this objective was to determine whether the effects of ageing on M cell development affect the ability to make IgA antibodies to antigens in the intestine. Our data show that aged mice have a highly significant reduction in the ability to make antigen-specific IgA responses to orally-administered antigens. These data suggest that ageing might dramatically reduce the efficacy of certain mucosal vaccines in elderly humans and animals.

Objective 4: in objective 4 we aimed to determine whether ageing might affect the composition of the commensal gut microbiota, and by doing so, influence M cell differentiation. Our data clearly show that the composition of the commensal gut microbiota has a significant influence of M cell development. Furthermore, manipulation of the composition of the commensal gut microbiota, or treatment with a microbial component can significantly improve M cell development, the ability to sample particulate antigens in the intestine, and importantly, significantly increase the ability to mount antigen-specific antibody responses to orally-acquired antigens.
Exploitation Route Our data may have significant interest to pharmaceutical and agri/healthcare companies. Mucosal immunity in the intestine is compromised by ageing and is associated with diminished antigen-specific IgA responses to pathogens and a decreased ability to generate tolerance to harmless antigens. Our data from this project identifying factors which can cause immunosenescence, or can improve immunity in elderly animals will be crucial for the development of mucosal vaccines to improve immunity in elderly humans and animals.
Sectors Agriculture, Food and Drink,Healthcare,Pharmaceuticals and Medical Biotechnology

 
Description I was invited to give a lecture on the effects of ageing on the mucosal immune system to the advanced course on diagnostic and therapeutic aspects of inflammatory Bowel Disease (IBD) in Badalona (Barcelona, Spain, November 2016). This course is specifically attended by healthcare professionals (nurses to consultants) involved in the management of these diseases. Approximately 300 IBD professionals attended this course.
First Year Of Impact 2016
Sector Healthcare
 
Description Determining the role of CSF1R-dependent macrophages in of Paneth cells and the
Amount £520,952 (GBP)
Funding ID MR/S000763/1 
Organisation Medical Research Council (MRC) 
Sector Academic/University
Country United Kingdom
Start 11/2018 
End 10/2021
 
Description Japan Partnering Award: Defining the factors that regulate M cell-development in the intestines of livestock
Amount £42,125 (GBP)
Funding ID BB/S019294/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 06/2019 
End 06/2023
 
Description Role of M cells in the sampling of mucosal antigens by B cells in Peyer's patches 
Organisation University of Gothenburg
Department Microbiology and Immunology UGOT
Country Sweden 
Sector Academic/University 
PI Contribution We provided our expertise in M cell immunobiology and use of unique in vivo systems to study M cells
Collaborator Contribution Prof. Nils Lycke is an expert in mucosal immunology and provided his unique systems in which to study the generation of antigen-specific IgA responses in the intestine.
Impact A revised manuscript has been submitted to Nature Communications (January 2019) describing how activated Peyer´s patch B cells sample antigen directly from M cells in the subepithelial dome to maintain gut germinal center responses
Start Year 2018
 
Description Study of M cell immunobiology and their role in mucosally-acquired infections 
Organisation Tohoku University
Department Graduate School of Medicine
Country Japan 
Sector Academic/University 
PI Contribution Dr. Atsushi Kobayashi worked within my research group for 2 years here at The Roslin Institute.
Collaborator Contribution Dr. Dr. Atsushi Kobayashi brought his expertise here for two years and worked as a visiting scientist in my research group.
Impact Several publications: DNA RESEARCH 19, 407-422, (2012); doi:10.1093/dnares/dss022 Mucosal Immunology 5, 216-225; doi: 10.1038/mi.2011.68 Mucosal Immunology 6, 1027-1037; doi:10.1038/mi.2012.141 Mucosal Immunology 6, 666-677; doi:10.1038/mi.2013.30
Start Year 2011
 
Description Study of M cell immunobiology and their role in mucosally-acquired infections (Emory) 
Organisation Emory University
Country United States 
Sector Academic/University 
PI Contribution We provided the ageing and prion disease pathogenesis mouse models
Collaborator Contribution Prof. Ifor Williams provided expertise in M cell immunobiology and mucosal immunology. Prof. Williams also provided unique M-cell-deficient mice (Vil1-Cre Rank-flox mice) as well as reagents to synthesise murine recombinant gst-RANKL. These were invaluable for the study of M cells in mice in vivo.
Impact Several publications: DNA RESEARCH 19, 407-422, (2012); doi:10.1093/dnares/dss022 Mucosal Immunology 5, 216-225; doi: 10.1038/mi.2011.68 Mucosal Immunology 6, 1027-1037; doi:10.1038/mi.2012.141 Mucosal Immunology 6, 666-677; doi:10.1038/mi.2013.30 Nat Nanotechnol. 2015 Apr;10(4):361-9; DOI: 10.1038/NNANO.2015.19 PLoS Pathog 12(12): e1006075; doi:10.1371/journal.ppat.1006075 Prof. WIlliams is also a named collaborator on the following BBSRC grants: BB/J014672/1 BB/M024288/1 BB/K021257/1
Start Year 2009
 
Description Study of M cell immunobiology and their role in mucosally-acquired infections (RIKEN) 
Organisation RIKEN
Department RIKEN Center for Integrative Medical Sciences (IMS)
Country Japan 
Sector Hospitals 
PI Contribution We provided the ageing and prion disease pathogenesis mouse models.
Collaborator Contribution Prof. Hiroshi Ohno and his colleagues provided expertise in M cell immunobiology.
Impact Several publications: DNA RESEARCH 19, 407-422, (2012); doi:10.1093/dnares/dss022 Mucosal Immunology 5, 216-225; doi: 10.1038/mi.2011.68 Mucosal Immunology 6, 1027-1037; doi:10.1038/mi.2012.141 Mucosal Immunology 6, 666-677; doi:10.1038/mi.2013.30 Prof. Ohno is also a named collaborator on the following BBSRC grants: BB/J014672/1 BB/M024288/1 and BBSRC Japan Partnering Award
Start Year 2007
 
Description Study of role of genes and transcription factors in M-cell development 
Organisation Keio University
Country Japan 
Sector Academic/University 
PI Contribution This collaboration aims to determine the role of genes and transcription factors in M-cell development in large animal species. Prof. Mabbott obtained a BBSRC travel award in 2017 to enable him to visit the Japanese partner Prof. Koji Hase in Tokyo, Japan, to discuss a potential collaboration. Prof. Mabbott through obtaining the travel award initiated this collaboration and provided the means to explore potential collaborations.
Collaborator Contribution Prof. Koji Hase, the Japanese partner, has provided his extensive expertise in the role of genes and transcription factors in M cell development. During my visit his institution also provided in-kind support for our meetings and small workshop. Since this visit our discussions have continued and a BBSRC Japan partnering award was submitted in November 2018 to provide further pump priming support.
Impact A BBSRC Japan partnering award was submitted in November 2018
Start Year 2017
 
Description Study of role of subepithelial mesenchymal stromal cells in M-cell development 
Organisation Hokkaido University
Country Japan 
Sector Academic/University 
PI Contribution This collaboration aims to determine the role of subepithelial mesenchymal stromal cells in M-cell development in large animal species. Prof. Mabbott obtained a BBSRC travel award in 2017 to enable him to visit the Japanese partner Prof. Sawa in Hokkaido, Japan, to discuss a potential collaboration. Prof. Mabbott through obtaining the travel award initiated this collaboration and provided the means to explore potential collaborations.
Collaborator Contribution Prof. Sawa, the Japanese partner, has provided his extensive expertise in subepithelial mesenchymal stromal cells. During my visit his institution also provided in-kind support for our meetings and small workshop. Since this visit our discussions have continued and a BBSRC Japan partnering award was submitted in November 2018 to provide further pump priming support.
Impact Submission of BBSRC Japan partnerinig award in November 2018.
Start Year 2017
 
Description Contribution to BBSRC opinion piece (BBSRC blog and in BBSRC Business Magazine) on the subject of "will I live forever?" 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact I provided comments to a request from the BBSRC press office on my scientific perspective to the question "will I live forever". These responses, and those from a range of other researchers in the field were published on-line on the BBSRC blog, and also as a feature in the October 2017 edition of BBSRC Business magazine.
Year(s) Of Engagement Activity 2017
URL https://bbsrc.ukri.org/news/fundamental-bioscience/2017/171024-f-will-i-ever-live-forever/?colour=re...
 
Description Gut cells are gatekeepers of infectious brain diseases, study finds 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Press release via the media describing our recent research published in PLoS Pathogens
Year(s) Of Engagement Activity 2016
URL http://www.bbsrc.ac.uk/news/health/2016/161214-pr-gut-cells-gatekeepers-of-infectious-brain-diseases...
 
Description Press release on publication describing effects of ageing on human immune system 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact A press statement was released describing our study published in the Journal of Allergy and Clinical Immunology on the effects of a drug, losmapimod, in improving immunity in the skin of elderly humans.
Year(s) Of Engagement Activity 2018
URL https://www.ed.ac.uk/roslin/news-events/latest-news/improving-vaccines-elderly-inflammation
 
Description Visit to Iowa State University to give talk and discuss my research 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact On October 8th 2018 I gave a talk to approx. 100 post-graduate students at Iowa State University in the Immunology and Neurobiology research programmes. I also attended small workshop group sessions with the students to discuss my science and also give career advice etc.
Year(s) Of Engagement Activity 2018