MICA: Fundamental Role of Phosphoinositide 3-kinase delta in Infection and Immunity: Insights from a Novel Primary Immune Deficiency Syndrome, APDS

Lead Research Organisation: University of Cambridge
Department Name: Medicine

Abstract

As a collaborative group of doctors, geneticists and scientists, we have recently discovered a new inherited disease, which causes increased susceptibility to infection. Affected patients suffer frequent and often severe bacterial infections of the lungs, sinuses and ears, often leading to permanent damage; they can also experience potentially life-threatening viral infections (particularly with the Herpes viruses such as those which cause chicken pox and shingles or glandular fever). Many of the patients die young from these devastating infections. We found that this disease is due to a genetic mutation that causes an enzyme called PI3Kdelta (which is found mainly in the cells of the immune system) to be more active and to 'work harder'. The overactive PI3Kdelta protein disturbs the chemical signals that control how immune cells develop and function in the body.
B and T lymphocytes coordinate the immune system to fight infections. We found that the B-lymphocytes from our patients do not make good quality antibodies (proteins which help to kill invading bacteria), and that their T-lymphocytes (which provide protection from viral infection) also function less effectively. We do not yet know how common the condition is, why the B and T cells don't work properly, or if other immune cells or lung cells are also affected. We also don't know if other abnormalities that affect the activity of PI3Kdelta or related proteins contribute to susceptibility to infection in a more general setting.
It is difficult to study immune cells from the patients, as most of them are unwell children, and because a feature of the disease is that the immune cells die rapidly outside the body. To solve this problem we have engineered a mouse with the same genetic defect, and will study how the immune cells of this mouse work. We will then take the findings from these mouse cells and see if they hold true in patients' cells; this strategy will enable us to use the limited number of patient cells available to us more effectively. We plan to expose the genetically altered mice to the same infections that the patients develop, to find out precisely why they are so susceptible. We will also test protective strategies such as drugs that reduce PI3Kdelta activity (PI3Kdelta inhibitors) to see if they prevent infection or reduce its severity. If this is the case, we will also treat patients who suffer from this disease with PI3Kdelta inhibitors and study the effects of this treatment; we believe such drugs will reduce the inflammation in their lungs and improve their ability to fight infection. Since too little PI3Kdelta activity is also detrimental immune, these medications will need to be carefully titrated, so we will need to monitor the effects on a range of biological markers of PI3Kdelta function as well as infection and inflammation.
This work will determine the role and importance of PI3Kdelta in infection. This knowledge will help not only patients with the newly described disease, but may also give new insights into why some otherwise healthy people are prone to develop bacterial and viral infections. This is of importance nationally and globally, since respiratory infections cause more illness and more deaths than all cancers combined.

Technical Summary

Background
Respiratory infections account for more than 6% of the global burden of disease, causing more morbidity and mortality than all cancers combined. We have recently described a novel combined immune deficiency characterised by severe recurrent respiratory bacterial infections, viral infections and a marked predisposition to B cell lymphoma; this condition is caused by an activating mutation (E1021K) in the gene encoding the catalytic subunit of PI3 kinase delta (p110delta) and has been termed 'Activated PI3 kinase Delta Syndrome' (APDS). We wish to elucidate precisely how augmented p110delta function compromises lymphocyte and myeloid immune cell function, and to explore the potential therapeutic applications of p110delta inhibitors in our patients.

Scientific Objectives.
We wish to establish the importance of augmented p110delta function in susceptibility to infection, to ascertain precisely how increased p110delta-dependent signalling perturbs lymphocyte and myeloid cell function, and to explore the role of p110delta inhibitors in the prevention/treatment of respiratory infection in APDS.

Plan of Investigation
We have generated a transgenic mouse model of the human disease and will use this to explore immune cell function, susceptibility to bacterial and viral infection, and protection from such infections by administration of p110delta inhibitors. In addition, we will undertake an experimental medicine study using a novel inhaled p110delta inhibitor to establish the ideal profile of inhibition needed to restore aberrant immune cell function; this strategy will be guided and monitored by means of a number of biomarkers including sputum PIP3 levels.

Potential Future Applications
This work will generate improved understanding of infection susceptibility at the genetic, biochemical and cellular levels, and will help to clarify the role of p110delta inhibitors in prophylaxis and treatment of infections in APDS.

Planned Impact

Who Will Benefit from this Research?
The overarching aim of the work described in this application is to delineate the role of PI3Kdelta in immunity and infection, and to explore its potential as a therapeutic target in immunodeficiency secondary to excessive PI3Kdelta activity. In addition to the accrual of scientific knowledge, this work may lead to novel diagnostic and therapeutic strategies in patients suffering recurrent respiratory infection, and other consequences of aberrant PI3Kdelta signalling. Given the burden of respiratory infection both within the UK and globally, this research has the potential to have a substantial and wide-ranging impact with multiple potential beneficiaries.
1. Patients suffering from the Activated PI3Kinase Delta Syndrome (APDS).
2. Additional patient cohorts suffering from recurrent infection or other consequences of aberrant PI3Kinase signalling.
3. Clinicians (respiratory physicians, immunologists and others) caring for the above patient groups.
4. Companies with an interest in developing and implementing novel diagnostic and therapeutic agents or strategies in these settings.
5. Government departments planning NHS strategy to implement care for conditions.
6. Academics studying the role of PI3kinase signalling in immunity, infection, inflammation and malignancy.

How Will They Benefit?
Direct benefit to patients with documented APDS is likely to accrue in the short term (within 3 years) as they are candidates for treatment with (already available) PI3K delta inhibitors; the identification of this patient group is likely to drive the development of improved therapeutic agents. The development of a transgenic mouse model will help to characterise the benefits of novel agents and compare them with existing compounds and other strategies such as vaccination. This research may also have implications for respiratory infection and infection susceptibility in the wider setting. There were an estimated 3.2 million deaths worldwide from lower respiratory tract infections in 2010, making this the third commonest cause of death globally, and bacterial pneumonia is the leading cause of childhood mortality worldwide.
This project includes development opportunities for the applicants through collaborative exposure to patient samples, to mouse models, to next generation sequencing platforms, and to novel assays. These skills will be shared among colleagues to support academic development in Cambridge and elsewhere. Methodologies and resources will be shared, to support UK academic excellence, raising the profile of UK-based research internationally.

Publications

10 25 50
 
Description Centre for Therapeutic Target Validation CTTV Project Grant
Amount £191,909 (GBP)
Organisation Centre for Therapeutic Target Validation 
Sector Academic/University
Country United Kingdom
Start 09/2015 
End 08/2017
 
Title E1020K transgenic mouse 
Description The E1020K mouse has been generated as a germline, and also under Cre-drivers specific for T, B and myeloid cells. The biochemical phenotype recapitulates that of the Activated PI3K delta syndrome (ie the mutation has been confirmed to be activating in the mouse). The contributions of the various cell types to streptococol infection have been established. Mice have been sent to another group with an interest in autoimmunity. 
Type Of Material Model of mechanisms or symptoms - mammalian in vivo 
Year Produced 2017 
Provided To Others? No  
Impact We are characterizing the behaviour of T cells, B cells and myeloid cells in further models. 
 
Title Prospective observational study on natural history, treatment and outcome of patients with APDS - a level 3 ESID registry study 
Description This registry is sponsored by the European Society for Immunodeficiency (ESID) with financial support from Novartis and GSK. It is a prospective study to collect longitudinal data on patients with the Activated Pi3Kinase Delta Syndrome. The database was designed and instrumented by the Principal Investigators, Professor Stephan Ehl (Freiburg, Germany), Professor Alison Condliffe (Sheffield UK) and Dr Sven Kracker (Paris, France). In line with targets, 50 patients had been captured in the database in 2017.The current figure has now risen to 85 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
Impact patients in the database provide a resource for prospective evaluation of this condition and has also been used for recruitment into clinical trials. An oral presentation was delivered at the European Society for Immunodeficiency (ESID) meeting in November 2017 and as a result a 'Perspectives' article was invited by 'Frontiers in Immunology' which is currently undergoing minor revision 
URL http://esid.org/Working-Parties/Registry/New-ESID-Registry
 
Description PI3K delta activity in airway epithelium 
Organisation University of Cambridge
Department Department of Physics
Country United Kingdom 
Sector Academic/University 
PI Contribution I have led a project with Professor Clare Bryant (Department of Veterinary Medicine, University of Cambridge) and Dr Pietro Cicuta (Department of Physics, University of Cambridge) to study Pi3K delta function in airway epithelial cells in the setting of infection. This has involved the use of Pi3K delta inhibitors. In future it will include tracheal tissue from transgenic mice that recapitulate the phenotype of APDS generated as part of the MRC grant
Collaborator Contribution Professor Bryant has supplied expertise with the pathogens and with airway cell culture. Dr Cicuta has supplied expertise with high speed microscopy and analysis of ciliary beat frequency
Impact We have preliminary data to apply for further grant funding.
Start Year 2015
 
Description PI3K delta activity in airway epithelium 
Organisation University of Cambridge
Department Department of Veterinary Medicine
Country United Kingdom 
Sector Academic/University 
PI Contribution I have led a project with Professor Clare Bryant (Department of Veterinary Medicine, University of Cambridge) and Dr Pietro Cicuta (Department of Physics, University of Cambridge) to study Pi3K delta function in airway epithelial cells in the setting of infection. This has involved the use of Pi3K delta inhibitors. In future it will include tracheal tissue from transgenic mice that recapitulate the phenotype of APDS generated as part of the MRC grant
Collaborator Contribution Professor Bryant has supplied expertise with the pathogens and with airway cell culture. Dr Cicuta has supplied expertise with high speed microscopy and analysis of ciliary beat frequency
Impact We have preliminary data to apply for further grant funding.
Start Year 2015
 
Title GSK 204745 
Description As part of our MRC MICA and in partnership with GSK, we have designed a clinical trial of the inhaled PI3K delta inhibitor GSK 204745 for use in patients with the rare primary immune deficiency syndrome APDS (Activated PI3Kinase delta syndrome). The trial is now open and recruiting. Because this is a rare condition, and in the light of new scientific evidence, we are currently applying to extend the age of participation to 12, and to include patients with the more recently described APDS2 (in which the regulatory subunit of PI3K delta is mutated rather than the catalytic subunit) 
Type Therapeutic Intervention - Drug
Current Stage Of Development Refinement. Clinical
Year Development Stage Completed 2015
Development Status Under active development/distribution
Impact We have used the inhaled inhibitor in wild type mice and found that is protected them from infection with Streptococcus pneumoniae. We are currently investigating the signficance of this finding. 
 
Description APDS website 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Contact from immunologists with possible patients to screen
Year(s) Of Engagement Activity 2013,2014,2015,2016
URL http://www.apdsyndrome.org/index.php/for-patients/learn-about-apds
 
Description Discussed animal research on Cambridge TV 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact I was interviewed for a programme aired on Cambridge TV about the use of animals in research.
Year(s) Of Engagement Activity 2016
URL http://www.cambridge-tv.co.uk/impact-animal-research/
 
Description Royal Society Summer Exhibition, 2015: Immune Army 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact We presented our exhibition: "Immune Army: weapons of microscopic destruction"; at the Royal Society Summer exhibition 2015. Many members of my lab participated in the design of the exhibition materials, the accompanying video (https://youtu.be/oMj8UxMPYJU) and at the exhibition itself. I spent two full days at the exhibition. Work on Activated PI3K Delta Syndrome (APDS) and Cancer immunotherapy from my lab featured prominently in this exhibition.
Year(s) Of Engagement Activity 2015
URL http://sse.royalsociety.org/2015/immune-army/