This project, named SENEDIT, aims to identify the key cellular and molecular mechanisms that control the immune surveillance of senescent cells, i.e. cells in irreversible cell proliferation arrest that accumulate in our tissues during aging. Rationale for SENEDIT Old age is accompanied by a multitude of age-related diseases. This represents an enormous challenge for individual care and for the public health system. At the cellular level, the accumulation of senescent cells (SCs) in tissues is emerging as a driver of age-related diseases. The accumulation of SCs in many tissues has already been shown to be a major factor in the induction or development of age-related diseases such as pulmonary fibrosis, renal fibrosis, neurodegenerative diseases, cancers and osteoarthritis. During aging, these SCs accumulate without our immune defenses being able to properly eliminate them, thus favoring the emergence of these diseases. Understanding the interactions between immune cells and SC is essential to counter the accumulation of SC in our tissues. This would allow the development of promising new "universal" therapeutic strategies to prevent or delay many age-related chronic diseases. The SENEDIT hypothesis The question we want to answer is: How does the immune system tolerate the accumulation of SCs during aging? Our new hypothesis is that SCs overexpress specific immunosuppressive molecular motifs that we call senescence immunological checkpoints (SICs) to escape immune surveillance. The SIC allow us to view the accumulation of these cells not as a passive phenomenon (increased incidence of senescent cells) but as an active mechanism that controls the fate of SCs by the immune system and alters the functionality of immune cells. Since the SCs accumulate in the tissues, they will be able to interact with our immune cells for a long time. The immunosuppressive or tolerogenic aspect of SICs leads us to believe that SCs will profoundly modify the state and function of our immune cells and that, in return, the immune cells will also modify the SCs. This hypothesis of mutual alterations and modifications, which we call "Senescence Editing" would accelerate the aging process and age-related diseases. Addressing the issue of SC accumulation as a disruption of immune tolerance induced by CIS is a real paradigm shift in the biology of aging. Our results would allow us to see the accumulation of SCs in our tissues with age as a simple passive mechanism of accumulation but as an active mechanism, associated with aging, which promotes their tolerance to the immune system. The realization of the SENEDIT project would allow to find the consequences of these interactions but also new molecules with SIC functions that would represent preferential targets to restore the immunosurveillance of SC. SICs thus open the way to a new class of therapeutic, diagnostic or theranostic biomarkers allowing to target several age-related pathologies. Beyond the knowledge of the fundamental mechanisms that regulate the accumulation of SCs, our results could be strongly valorized (patent, start-up creation, clinical trials) by proposing innovative solutions for the treatment of various age-related diseases.

The objective of this project is to design, characterise and functionally test new nanoscale agents based on single domain antibodies (nanobodies, Nbs), coupled to DNA scaffolds (DNAnobodies) for applications in immunology. The function of immune cells is tightly regulated by biomolecular recognition and signaling at cell-cell contacts, but emergent factors like geometry, multivalency and mechanical forces intervening at this interface are still poorly understood. The multiscale structures from single ligand-receptor bonds to supramolecular architectures, as well as the entanglement of biochemical and physical mechanisms at the nanoscale render functional studies difficult and the design of new therapeutic agents targeting this interface haphazard. We hypothesize that new nanotools are required to advance knowledge in those fields. DNAnobodies will help systematise fundamental studies as well as therapeutic design, since they offer a high control of specificity, reactivity, stoichiometry, architecture, and mechanics at the immune cell surface. This new family of hybrid nano-objects has a great potential for applications in both fundamental biology and therapeutics.

Cholesterol is an essential lipid for life, participating not only in the structuration of membranes, but also as a precursor in the synthesis of steroid hormones, bile acids, and oxysterols. Oxysterols are cholesterol oxidation products that represent a growing family of metabolites. Recently, we discovered a new metabolic branch in the cholesterol pathway, which is that of 5,6-epoxycholestanols (5,6-EC). Indeed, we have shown that the alpha isomer of 5,6-EC can be conjugated enzymatically with biogenic amines such as histamine and spermidine, to form dendrogenins A and B (DDA and DDB), respectively. These compounds appear to be extremely potent inducers of cell differentiation. As part of the DASYNT2 project, we identified the enzyme responsible for the production of dendrogenin A, demonstrated other bioactive conjugation products, and confirmed their existence as metabolites in mammals. The DASYNT3 project aims to continue the exploration of this metabolic pathway by: 1) characterizing the enzymes involved in the biosynthesis of the identified dendrogenin subgroups (DDA to DDC), 2) continuing to identify new conjugates and determine their presence in mammalian metabolism, 3) defining their biological properties, and 4) elucidating their mechanism of action at the molecular level. Upon the conclusion of this project, we will present the scientific community with a comprehensive overview of this metabolic pathway, thereby ushering in new avenues of research and providing new tools for illuminating previously undisclosed mechanisms involved in the onset of degenerative diseases and aging processes.

Indoor exposure to mould and dampness in dwellings are a risk factor for the development and/or evolution of several respiratory diseases (including asthma and rhinitis). Added to the negative effects on health, strong social inequalities are related to mould exposure. In order to design effective policies to prevent development of indoor mould and reduce its impacts on public health in France, it is essential to gain a better understanding of this issue. In this context, we propose to investigate mould contamination in dwellings in France using two sources of data, i.e. i) dwelling, geographical, socio-economic characteristics and health outcomes collected using standardized questionnaires in ~118 000 participants of the National French Constances cohort (www.constances.fr), ii) a large scale quantitative and qualitative objective assessment of mould contamination using electrostatic dust collectors (EDCs) which will be exposed several weeks in dwellings among 2000 Constances participants’ dwellings, selected according to the presence or absence of visible moulds or of factors associated with mould development. In fine, this holistic approach will bring new data on mould contamination in French dwellings, spatial distribution of mould contaminations, population at risk, as well as a clarification of the determinants of mould contamination and of the respiratory health effects of mould exposure, especially in diseases poorly documented other than asthma and rhinitis. These data will be used to set-up an online training platform on the assessment and management of mould in dwellings, in order to improve the knowledge of the general public and professionals involved in the field.

Alzheimer’s disease (AD) is the most common neurodegenerative disorder associated with dementia, cognitive decline and memory loss. AD is characterized by the pathological formation of intraneuronal aggregates of tau protein and extracellular aggregates of amyloid ß (Aß). The view of the brain as an immune-privileged organ has moved towards a pivotal role of the crosstalk between brain-resident and peripheral immune cells in both physiological and pathological conditions. Hence, better understanding the peripheral-central immune crosstalk is crucial to develop new therapies in neurological conditions. In this line, B cells are found in the brain of AD patients and AD-like mice, although their impact on disease progression remains unclear and their manipulation led to controversial results. As resident immune cells of the central nervous system (CNS), microglia are primarily responsible for phagocytotic clearance of Aß. However, there is an increasing recognition that exacerbated neuroinflammation and dysfunction of microglia play a critical role in AD. Our lab has recently developed an experimental protocol in which B cells are cultured in vitro to become anti-inflammatory. Our preliminary data indicate that these B cells exert potent anti-inflammatory effects in the central nervous system, downregulate microglial AD relevant genes and improve cognitive deficits in AD-like mice. In light of these data, our objectives are i) to deeply characterize the phenotypes and functions of B cells infiltrating the brain of AD-like mice at different disease stages, ii) to test whether such anti-inflammatory B cells can positively impact disease development and/or progression in models of AD-like pathology and iii) to characterize phenotypically and functionally B cells at the periphery along disease progression in AD patients, in order to highlight potential correlations with clinical presentation and disease severity. The iBregAD project aims to pioneer a novel immunotherapy for AD by harnessing in vitro anti-inflammatory B cells. This innovative approach seeks to modulate neuroinflammation and neurodegeneration, offering a novel approach to disease modification. By influencing CNS environment, anti-inflammatory B cells hold potential in attenuating the neuroinflammatory processes characteristic of AD. Chronic neuroinflammation is widely implicated in AD progression, contributing to neuronal damage and cognitive decline. Through their ability to mitigate neuroinflammation, anti-inflammatory B cells may offer neuroprotective benefits, preserving neuronal integrity and retarding disease advancement. Notably, our project stands out for its originality and ambition in elucidating the intricate interplay between B cells in peripheral and central immune systems. Additionally, it aims to unravel the cellular and molecular mechanisms through which anti-inflammatory B cells orchestrate CNS inflammatory remodeling during AD progression. This deeper understanding not only enhances our comprehension of the disease but also holds promise for identifying novel biomarkers crucial for advancing therapeutic interventions, ultimately enhancing the quality of life for patients.