Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - MITOMAD (Functional characterisation of mitochondrial metabolic adaptations to innate sensing in dendritic cell subsets)

Teaser

The general issue being addressed by our project is how dendritic cells (DCs) and macrophages sense the tissue environment and microbial, how they translate this sensing into metabolic signals, with a particular focus on mitochondrial metabolism, and how this knowledge can be...

Summary

The general issue being addressed by our project is how dendritic cells (DCs) and macrophages sense the tissue environment and microbial, how they translate this sensing into metabolic signals, with a particular focus on mitochondrial metabolism, and how this knowledge can be applied for improved immunotherapy. This project aim to identify new targets to exploit DCs for improved immunotherapy and this may generate new therapeutic strategies in diseases related to the immune system, ranging from tackling antibiotic-resistance by learning about the metabolic requirements of trained immunity, modulating responses to dampen immunity in autoimmunity, chronic inflammation or asthma, or enhancing immunity against tumors. The overall objectives are:
1. Characterize the metabolic reprogramming after DC stimulation, with particular emphasis in analysis of mitochondrial metabolism.
2. Dissection of molecular mechanisms connecting innate sensing and mitochondrial adaptations in DCs.
3. Analysis of the impact of manipulation of mitochondrial biology on DC metabolism and function.
4. Assess the functional in vivo effects of targeting mitochondrial biology in DCs in homeostasis and disease.

Work performed

In relation with the previous mentioned objectives, the main results obtained are:
1. We are characterizing the metabolic reprogramming upon DC and macrophage stimulation with different stimuli that mimic pathogen associated molecular patterns and tissue damage signals. We have found stimuli that induce the glycolytic switch described for LPS, while others rather induce other types of metabolic rearrangements. For instance, we are further exploring how some Dectin-1 ligands may induce changes in mitochondrial activity. In a related work, we found that WGP (whole glucan particles), a Dectin-1 agonist, a Dectin-1 agonist, triggers trained immunity in macrophages and therefore this could suggest that mitochondrial reprogramming induced by WGP is involved in trained immunity (Saz-Leal et al. Cell Reports. 2018).
2. Following the preliminary results obtained in the previous objective, we are selecting the stimuli that are more appropriate for the proteomic analysis of the changes in mitochondrial interactome following these stimuli. We are also targeting in a bias approach pathways that are important for metabolic reprogramming. As the HIF-1a pathway is crucial for this reprogramming, we deleted the HIF regulator VHL in DCs and some macrophage subsets using the CD11cCre driver. While we have not found a relevant phenotype so far in DCs, we found that alveolar macrophages were not terminally differentiated upon HIF-1 and HIF-2 stabilization in normoxia in this context (Izquierdo et al. Cell Reports. 2018). These results guide some more metabolic analysis on how this process is regulated.
3. In this area of research on how DCs sense the environment and how is the impact in their function, we have had related results describing how sensing of tissue damage by cDC1s results in control of neutrophil infiltration (Del Fresno et al. Science. 2018). This represents a new function of DCs that is being analysed from the perspective of how metabolic manipulation of DCs can affect this functional readout. In addition, Mincle sensing of microbiota leads to production of IL-6 and IL-23 that regulate Th17 and ILC3 in the gut (Martínez-López et al. Immunity. 2019), offering new functional pathways which dependency on mitochondrial metabolism is being analysed. We are actively working in how targeting mitochondrial complexes can affect DC and macrophage function.
4. Targeting DCs for immunotherapy is one of the key aspects of the proposal. In this regard, one of our major interests is DC vaccination in cancer and we have set up the use of cDC1s in cancer immunotherapy using a novel protocol that could be potentially extended to humans (Wculek et al. JITC. 2019). We are working on how DC function can be affected by metabolism and how we can target this by using nanoparticles.

Final results

In relation with the previous mentioned objectives, the progress and expected potential are:
1. We have characterized how innate stimuli lead to distinct metabolic signatures and have described modulatory mechanisms that affect metabolic reprogramming and trained immunity (Saz-Leal et al. Cell Reports. 2018). The potential impact of SHIP-1 regulation of metabolic reprogramming is the use of SHIP-1 inhibitors to boost trained immunity, a topic that we are currently exploring. A patent that we have filled in protects the use of SHIP-1 inhibitors to boost trained immunity.
2. In our bias approach we have established the involvement of the HIF-1 pathway in alveolar macrophage function and the importance of sensing oxygen for terminal differentiation (Izquierdo et al. Cell Reports. 2018). These results open a new perspective on the role of glycolysis in macrophage function and we will further analyse the metabolic implications and functional consequences.
3. We have found a new function in inflammation of DCs (Del Fresno et al. Science. 2018) and a new pathway of sensing microbiota that affects immunity in the gut (Martínez-López et al. Immunity. 2019). This has potential impact as new functional targets that can be affected by the manipulation of mitochondrial metabolism, and we are currently exploring this avenue.
4. Our work has established that cDC1s can be effectively used for cancer immunotherapy (Wculek et al. JITC. 2019). The potential is to manipulate metabolism in cDC1s to improve cancer immunotherapy.