Deciphering the function(s) of the C-type lectin DCIR/CLEC4A in tuberculosis

Periodic Reporting for period 1 - BREFMC2017 (Deciphering the function(s) of the C-type lectin DCIR/CLEC4A in tuberculosis)

Periodo di rendicontazione: 2018-06-01 al 2020-05-31

Tuberculosis (TB), caused by the infectious agent Mycobacterium tuberculosis (Mtb), is a devastating disease and one of the leading causes of death in the developing world. Immune cells play a key role in anti-mycobacterial immunity and express a range of pattern-recognition receptors, which are involved in the recognition of Mtb antigens. Dr Neyrolles’ lab has characterised a number of these receptors, with the most recent being, and the focus of this project, the Dendritic Cell Immunoreceptor (DCIR) with the aim of deciphering its role in Mtb immunity. They have demonstrated that when compared to wild-type (WT) mice, mice inactivated in the DCIR homolog (mDCIR1-KO) display increased antimycobacterial immunity as a result of an impaired response to type I interferon and an increased production of IL-12. Consequently, mDCIR1-KO mice control Mtb better than their WT counterparts, but also develop increased lung inflammation. Based on these findings, it was hypothesised that DCIR is a key regulator of the balance between type I and type II interferon responses, which is not only relevant in the context of TB, but in non-infectious inflammatory diseases.

Currently, there are two billion people infected with TB worldwide, with 1.8 million people dying from TB every year. Additionally, TB is one of the leading causes of death in HIV positive patients globally. One of the major problems associated with this disease is that treatment for TB requires an intense and prolonged course of antibiotics that is highly dependent upon strict compliance by the patient. This can be quite difficult when a typical treatment consists of several antibiotics taken every day for up to 6 months, with no guarantee of complete clearance of the disease. Additionally, the persistence of TB can be attributed to a number of factors, one of which is its growing resistance to these antibiotics. Therefore, the development of novel strategies to treat this devastating disease are required.

The revised aim of this project is to investigate the ligand of human DCIR and a murine homolog, mDCIR1, in order to better understand the function(s) of this receptor.
At the conclusion of this project, the ligand for DCIR, both in human and mouse, has been identified and the biological significance of this interaction is currently being investigated.

"The BREFMC2017 project was composed of eight work packages (WP), which were conducted from June 1st, 2018 until May 31st, 2020. It should be noted that, due to the impact of COVID-19, a number of WPs were significantly affected (approximately 10% of total bench time was lost).

Training.

During the first year of my project, I undertook a training session for the use of the class 3 animal facility (ASB3) at the Institute of Pharmacology Structural Biology (IPBS). This training consisted of the appropriate entry of the facility, as well as the use of appropriate personal protective equipment and safety precautions in the event of an emergency. Furthermore, I underwent the appropriate medical examinations so that I was certified to work in this facility. I also completed the course entitled ‘Training for animal handling and experimentation (English)’, and achieved a score of 51.75/60; one of the highest in the class.

Scientific Results.

To date no ligand for DCIR has been identified, and so we employed a multifaceted approach to identify this ligand(s). Initially, we aimed to identify the ligand(s) of human DCIR and a murine homolog. This was accomplished using cutting-edge quantitative mass spectrometry and yielded a number of putative candidates. These candidates were then individually validated in order to confirm the identity of the ligand. The nature of the interaction between DCIR and its ligand was investigated using sophisticated super resolution microscopy, molecular biology and cell biology. Finally, the functional role of DCIR and its ligand was investigated, with a specific focus on the induction of various signalling pathways. Collectively, these experiments demonstrated that DCIR may influence numerous innate immune sensing pathways in immune cells through the binding of its ligand.

Advanced training.

As mentioned above, the course entitled ‘Training for animal handling and experimentation (English)’ was completed with high distinction. Additionally, I attended a workshop on R/RStudio that was run internally at the IPBS. This was a 3-day workshop that introduced the fundamentals of R as well as employing this package to analyse large datasets. I attended the EMBO Workshop entitled 'Pathogen Immunity and Signalling' held in Oxford, UK during April 1-5 2019. This was a 4-day conference attended by experts in the field of innate immune responses to pathogens and presented great networking possibilities. Specifically, a 'meet the speaker' dinner was held and allowed me to speak with a number of experts and have their feedback on my project. Other informative sessions included a forum with editors of prestigious journals such as Nature Microbiology, Science Immunology, and Journal of Experimental Medicine. This was a highly rewarding experience for myself and my research.

Outreach

I was selected as a finalist for the Falling Walls Lab Marie Skłodowska-Curie Actions for my talk entitled 'Breaking the Wall of Tuberculosis'. This competition took place during the European Research and Innovation Days in Brussels, Belgium from 24-26 September, 2019. This marked the first of these events held by the European Commission with the hope to bring together ""stakeholders to debate and shape the future research and innovation landscape"", as stated on their website.

Publications and conferences.

The book chapter entitled 'C-type Lectins in Immunity to Lung Pathogens' was published in the review series Current Topics in Microbiology and Immunology in 2020. Due to COVID-19, the original research paper that was planned to be submitted this year was hampered significantly. This manuscript is still being prepared and will be submitted at the end of the year.

It was planned to attend and present an oral presentation at the EMBO conference 'Innate Immunity in Host-Pathogen Interactions' that was to take place in Heidelberg, Germany 28 June - 1 July, 2020. Unfortunately, this conference was cancelled due to COVID-19 and will not be rescheduled. Additionally, there are no opportunities to attend a conference or present this year due to COVID-19."

Tuberculosis (TB) is a globally devastating disease that is still a threat today. At its core, Tuberculosis is an immunopathology, and so in order to better treat this disease, a better understanding of the host immune response to this disease is required. The work of our lab has clearly shown that DCIR plays an important role in the fine-tuning of the immune response during infection with Mycobacterium tuberculosis. BREFMC2017 has paved the way for future studies to begin to exploit DCIR as an immunomodulatory checkpoint for the rationale design of host-directed therapeutics aiming at reducing lung inflammation in adjunctive therapies with more classical antibacterial drug regimens. This would have far-reaching socio-economic benefits in areas where Tuberculosis is still a major issue. Additionally, as suggested above, the role of DCIR is most likely not specific to TB immunity, and thus, our results will be exploited in the context of other infectious and non-infectious inflammatory disorders.

Presentation of the project at Falling Walls Lab Marie Skłodowska-Curie Actions

Periodic Reporting for period 1 - BREFMC2017 (Deciphering the function(s) of the C-type lectin DCIR/CLEC4A in tuberculosis)

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