Circulating TNF-α, CCL2 and IL-6 are associated with blood-based epigenetic age and targeted CpG methylation signatures in aging mice.

Aging is characterized by profound biological changes, among which epigenetic remodelling -encompassing alterations in DNA methylation patterns and microRNA modulation - and inflammaging(definition) (chronic, low-grade systemic inflammation) represent major contributors to functional decline and the pathogenesis of age-related diseases. While increasing evidence suggests a complex interplay between epigenetic modifications and inflammaging, a comprehensive elucidation of this axis remains elusive. In this study, we investigated the relationship between age-related epigenetic changes and systemic inflammation in the blood of mice across a lifespan trajectory, from adulthood (12 months of age) to extreme old age (33 months of age). We identified significant positive associations between epigenetic age (estimated via the multi-tissue DNAge® panel, covering ∼2000 CpG loci) and three key pro-inflammatory mediators: TNF-α, CCL2, and IL-6. In age-adjusted multivariable regression models, TNF-α was the only mediator retaining a significant independent association with DNAge®. Targeted methylation analysis within the DNAge® CpG panel showed that TNF-α was associated with a larger number of cytokine-associated CpGs than CCL2 and IL-6, with stronger statistically detectable effects in females. Finally, an exploratory analysis showed positive correlations between circulating TNF-α levels and two inflammation-related microRNAs, miR-155 and miR-21. Collectively, these findings indicate that circulating TNF-α, CCL2, and IL-6 are associated with blood-based epigenetic age in advanced aging, and identify TNF-α as the strongest inflammatory correlate among the three mediators examined in this study.