Role of chronic intermittent hypoxia on cell senescence and age-related diseases – OSAGING

Obstructive sleep apnoea (OSA) syndrome is a common disorder (6-12 % of adults) in which recurrent apnoea and hypopnoea produces repeated hypoxaemia episodes followed by re-oxygenation. These hypoxaemia/re-oxygenation cycles induce oxidative stress, a major contributor to OSA-related morbidity and mortality. We recently demonstrated that recurrent intermittent hypoxaemia in OSA promotes the induction of cell senescence. Previous work by our groups supports an association between sustained hypoxia and increased cell senescence in the lung, heart, and eyes, with aberrant cytokine release as part of the senescence-associated secretory phenotype (SASP). We propose here to demonstrate that chronic intermittent hypoxia (CIH)-induced cell senescence is the key factor promoting OSA-related cardiovascular, lung, and ocular comorbidities, including age-related macular degeneration (AMD), a disease strongly associated with OSA.
Our goal is to demonstrate that CIH induces cell senescence and organ dysfunction and that genetic or pharmacological elimination of senescent cells (SCs) during CIH prevents or corrects inflammation and the cardiovascular, pulmonary, and ocular complications of OSA.
Aims:
1) To demonstrate that CIH mimicking severe OSA in mice leads to SC accumulation and exaggerated immune-cell infiltration in lung, cardiovascular, and retinal tissues. Using p16luc/+ knock-in mice and p16GFP INK ATTAC mice expressing luciferase and green fluorescent protein in senescent cells, we will investigate SC accumulation kinetics and determine the CIH threshold that triggers cell senescence. The appearance of SCs will be monitored in vivo using luminescence imaging (lung) and scanning laser ophthalmoscopy (retina). We will quantitate the cell type-specific appearance of SCs using cytometry and immunohistochemistry in the immune system (leucocytes, bone marrow, and spleen) and in the lung, heart, and eyes; and assess SASP components, DNA damage (DDR) in genomic and telomeric DNA, very short telomeres (TESLA technique), and oxidative stress in each tissue.
2) To evaluate whether blocking cell senescence in p16-deficient mice (p16luc/luc mice) or eliminating SCs by activating the killer gene construct in p16-INK-ATTAC mice alleviates CIH-induced functional and morphological alterations in cardiac, pulmonary, and retinal tissues. Both preventive and curative protocols will be assessed under normal, strenuous (aged or obese mice and mice exposed to strong but not toxic lighting conditions), and inflammatory (laser-induced subretinal inflammation) conditions combined with CIH. Mice will be investigated for lung alterations (fibrosis, emphysema, vascular remodelling), cardiac structural and functional parameters, retinal function and morphology (laser- and light-induced subretinal inflammation, choroidal neovascularisation, and retinal pigment epithelium /photoreceptor degeneration), and for the parameters assessed in aim 1.
3) To determine the respective roles for tissue-cell senescence versus bone-marrow-derived immune-cell senescence using CIH-exposed chimeric wildtype mice grafted with p16-deficient- and p16-INK-ATTAC bone marrow and vice versa.
4) To explore whether systemic or locally administered senolytic drugs can serve to treat the cardiovascular, lung, and retinal complications of OSA. We will test whether local administration of the newly designed FOXO4-p53 interfering peptide, given by inhalation to specifically target the lung or intravitreally to specifically target the diseased retina, effectively kills SCs and prevents and reverses the lesions without causing systemic effects.
Impact
We will demonstrate that OSA is a major source of premature and pathological ageing; show causality between SC accumulation during CIH and lung, cardiac, and ocular diseases, including AMD; delineate the role for tissue versus immune SCs, and explore locally administered senolytics as novel therapeutics for AMD and lung disease.