Mitochondria are crucial for ATP production and intracellular signaling in higher eukaryotic cells. These organelles contain genetic material that reflects their bacterial ancestry, including mitochondrial RNA (mtRNA). Under normal conditions, mtRNA is tightly confined and processed within mitochondria, ensuring the proper synthesis of proteins required for oxidative phosphorylation. Recent evidence suggests that mitochondrial stress may promote the leakage of mitochondrial components, including mtRNA. Once released into the cytosol, mtRNA can be sensed by cytosolic pattern recognition receptors (PRRs), thereby activating signaling pathways that promote the production of pro-inflammatory cytokines.
Although these mechanisms have been investigated mainly under conditions of acute stress, the specific contribution of mitochondrial dysfunction and mtRNA release to chronic low-grade inflammation and cellular senescence during physiological aging remains incompletely understood. This represents an important knowledge gap in the understanding of molecular processes that may contribute to age-related inflammation and functional decline.
The MIRACLE project includes a broade series of preclinical in vitro and in vivo experiments aimed at clarifying the mechanisms linking mitochondrial dysfunction, mtRNA release, inflammatory pathway activation, and cellular senescence during aging. These experimental activities are designed to define the biological pathways involved and to identify potential strategies capable of modulating mtRNA-associated inflammatory and senescence responses.
Within this broader framework, the present human study is intended to corroborate and extend the preclinical findings in humans. To this aim, adult participants across different age groups will be enrolled, and skin biopsy and blood samples will be collected to obtain skin-derived fibroblasts, peripheral blood mononuclear cells (PBMCs), serum, plasma, and whole-blood RNA.
Skin-derived fibroblasts will provide an accessible primary cell model for the investigation of age-related cellular and molecular changes. Fibroblasts isolated from participants of different ages will be used to assess mitochondrial function, mtRNA release, inflammatory signaling, and markers of cellular senescence. PBMCs collected from the same participants will be analyzed as a complementary blood-derived cellular model to evaluate systemic immune and inflammatory features, including immunosenescence-related signatures. Serum and plasma samples will be used to measure circulating inflammatory mediators and senescence-associated factors, while whole-blood RNA will be used to assess systemic transcriptional signatures related to inflammation, type I interferon activation, mitochondrial stress response, immune aging, and senescence-associated pathways.
